who is content pretending that he will eventually become an enormous success, Biff takes responsibility for his failures and attempts to reveal the truth to his father. Both Biff and Happy's failures reflect their upbringing and are a result of Willy allowing them to steal, cheat, and take advantage of others when they were adolescents. Willy failed to instill the values of hard work, selflessness, and dedication in his sons, which negatively influenced their perception of the world. Biff and Happy grew up believing that being well-liked was the most important thing in life, which was terrible advice from Willy and contributed to their numerous struggles once they entered the competitive business world.

Biff and Happy have very different personalities, and this also affects the way each of them treat their father, Willy Loman. Happy's name is very significant-he is a happy-go-lucky character, he ignores unpleasant things in life and just focuses on what is pleasant and what makes him happy. Biff, on the other hand, feels very unsatisfied with his life and blames his father for a lot of the unhappiness.

In the first conversation between Biff and Happy at the beginning of the play, they discuss their father:

HAPPY: You’re not still sour on Dad, are you, Biff?

BIFF: He’s all right, I guess. 

We can see here that Happy has a better relationship with Willy than Biff does. They go on to say,

BIFF: Why does Dad mock me all the time?

HAPPY: He’s not mocking you, he...

BIFF: Everything I say there’s a twist of mockery on his face. I can’t get near him.

HAPPY: He just wants you to make good, that’s all. 

Happy defends Willy, while Biff criticizes him.

Biff also stands up to his father, while Happy either remains silent or tries to make everyone calm. Biff gets upset when Willy yells at Linda, and Biff says, "(furiously): Stop yelling at her!" Shortly before that, Happy says, "(trying to stop them): Wait a..." Happy just wants everyone to get along.

It is important to note that we learn through flashback about an incident that happened right after Biff graduated high school that changed Biff and Willy's relationship for forever. Willy was away on a trip, and he was staying in a hotel with his mistress, "The Woman," as she is called, and Biff went to find Willy because he needed help. Biff discovered the woman in Willy's hotel room, and after that lost all respect for his father. Before that, he had idolized him. But when he discovers his father is cheating, Biff says to him, "You fake! You phony little fake! You fake!" Happy, however, remains ignorant of this (as far as we know), so he still respects his father.

At the end of the play, in the last scene with the whole Loman family, they fight. Biff confronts his father about the piece of rubber tube that Linda had found that Wily was going to use to kill himself. In this scene, we again see Biff angry and confronting his father, while Happy tries to maintain the peace:

WILLY (sinking into a chair at a table, with full accusation): You’re trying to put a knife in me — don’t think I don’t know what you’re doing!

BIFF: All right, phony! Then let’s lay it on the line. (He whips the rubber tube out of his pocket and puts it on the table.)

HAPPY: You crazy...

LINDA: Biff! (She moves to grab the hose, but Biff holds it down with his hand.)

BIFF: Leave it there! Don’t move it!

WILLY (not looking at it): What is that?

BIFF: You know goddam well what that is.

WILLY (caged, wanting to escape): I never saw that.

BIFF: You saw it. The mice didn’t bring it into the cellar! What is this supposed to do, make a hero out of you? This supposed to make me sorry for you?

WILLY: Never heard of it.

BIFF: There’ll be no pity for you, you hear it? No pity!

WILLY (to Linda): You hear the spite!

BIFF: No, you’re going to hear the truth — what you are and what I am!

LINDA: Stop it!

WILLY: Spite!

HAPPY (coming down toward Biff): You cut it now!

BIFF (to Happy): The man don’t know who we are! The man is gonna know! (To Willy) We never told the truth for ten minutes in this house!

HAPPY: We always told the truth! 

We see instances throughout this scene of Biff treating Willy in an angry and disrespectful way (although we can understand some of his frustration), and Happy just wants everything to be okay. So the main difference in how the two brothers treat their father is that Happy treats his father as though nothing is wrong, whereas Biff can't take it anymore and feels the need to speak the truth to his father.

Biff is Willy Loman's oldest son, and he is an insecure man without a steady job or relationship. In the play, Biff returns home and is depicted as a lost, confused, desperate individual. As an adolescent, Biff excelled at sports and was a popular, enthusiastic boy. Unfortunately, Willy did not instill the proper values in his son and instead praised his popularity. Biff's dreams of playing college football came to an end after he failed a high school math course and discovered that his father was having an affair. As the play progresses, Biff comes to terms with the reality of his situation and life. By the end of the play, Biff refuses to live a delusional life and lie to himself. He accepts the fact that he is a deceitful thief and leaves home hoping to change the trajectory of his life for the better.

Happy is Willy's youngest son, and he is a delusional, dishonest man. Happy is a few years younger than Biff and works as an assistant (although he claims to be the assistant buyer of the company). He brags about sleeping with the executives' fiancées and thrives on sexual gratification. Unlike his brother, Happy is unapologetic and refuses to accept reality by taking responsibility for his actions. Happy's arrogance and lack of self-reflection make him a less sympathetic character than Biff. Happy does not feel bad about engaging in affairs and is content with living a lie. Unlike Biff, who has a tortured soul from years of being selfish, Happy refuses to acknowledge his faults.

While both Biff and Happy resemble their father, Willy, it is Happy who stubbornly maintains his similarity to Willy in the end. We see this in Happy's speech at the funeral. 

"I’m gonna show you and everybody else that Willy Loman did not die in vain. He had a good dream. It’s the only dream you can have—to come out number-one man."

Biff, at this point, has realized his limitations. He has seen himself for who and what he is. This is a big step for Biff and it is a step that Happy fails to make. 

During the action of the play, Willy is seen encouraging both of his sons to maintain an exaggerated view of their personal qualities. Willy supports the illusion that Biff was an important figure at the sporting goods store at one time. Biff believes this fiction as well until his actually goes to the sporting goods store and talks to his old boss. 

"And then he gave me one look and—I realized what a ridiculous lie my whole life has been. We’ve been talking in a dream for fifteen years. I was a shipping clerk."

Biff recalls this moment when he is talking to Happy in a restaurant. In this episode, Biff tries to explain to Happy then to Willy that he is now done with the illusion. He can see now that he is not "great". He is just a normal guy, with normal limitations. This, for Biff, is a liberation and a positive realization. Willy takes it as a chastisement and an act of spite. 

Here we see the break. Biff chooses reality. Happy chooses, like Willy, to maintain an illusion, preferring to believe in his own (potential) greatness.

I personally think there are more similarities than differences, so you might want to think about the ways in which they are actually rather similar as well as being different too. However, there are some distinctive differences that are well worth drawing out.

The first is that obviously Willy is completely delusional. The way in which he is presented at the beginning of Act One in this play indicates that he has rather a fluid relationship with both time and facts. Consider the way that he contradicts himself so blatantly, in the space of a few seconds, saying, for example, that Biff is "a lazy bum!" on the one hand then saying "There's one thing about Biff--he's not lazy." Also, think of the way in which he slips back into the past to retreat into a happier existence.

Biff is a character who finds it difficult not to steal and also does not seem to be able to find success in his life. He has just worked in a series of farm jobs and has never managed to get the kind of city job that would give him prestige and success that his father would like for him.

Finally, Happy, although he does have a job in the city, is trapped in a low position and is left waiting for his boss to die. He deliberately sleeps with the wives and fiancees of his superiors and is very much lost in his life. Note what he says in this quote:

But then, it's what I always wanted. My own apartment, a car, and plenty of women. And still, goddammit, I'm lonely.

Happy therefore, in spite of his apparent success, actually leads a very hollow life, as he identifies in this quote.

The contrast between the ways that Biff and Happy treat their father helps the audience understand the deeply dysfunctional quality of the family and the flaws in Willy’s interpretation of success. The differences between the sons’ communication with Willy are most evident in the restaurant scene, when Biff tries to be honest but Happy continues to say what he thinks his father wants to hear.

Both sons have been strongly affected by their father’s conviction that popularity and ambition matter more than hard work. Neither of them invests as fully in the American Dream as their father did. Their attitudes were shaped by their father’s dissatisfaction and constant criticism of their apparent lack of success. Because the sons’ experiences significantly diverged at one point, however, their attitudes toward Willy and treatment of him likewise differ.

Biff became deeply disillusioned about the father he once admired when, as a teenager, he found out about his father’s affair. This secret and the associated knowledge of Willy’s hypocrisy proved too great a burden for Biff to overcome. Happy, however, remained unaware of his father’s duplicity. Although he understands that Willy never managed to meet his own standards, he is moderately critical of Willy. Further, the father’s expectations of his younger son were lower than for Biff, and Happy grew up satisfied with having grandiose fantasies but remaining an underachiever.

Death of a Salesman is a 1948 drama written in two acts and a requiem by American playwright and essayist Arthur Miller and first produced in 1949. As it covers darker themes such as suicide, lies, identity, betrayal, secrets, anger, misconception of reality, tragic love, and abandonment, the play is considered a tragedy. The play has gained tremendous commercial success and critical acclaim and even won the 1949 Pulitzer Prize for Drama and the Tony Award for Best Play. Death of a Salesman is considered one of the most influential and popular plays of the twentieth century. It tells the story of sixty-three-year-old recently demoted salesman Willy Loman, who lives under the illusion that he is a successful man, and his family, which consists of his devoted wife, Linda, and his equally unsuccessful sons, Biff and Happy.

I believe that the most interesting element of Biff and Happy’s characterization is that they represent two halves of Willy’s personality. Happy is the younger brother who has basically lived the majority of his life in the shadow of his big brother, Biff. He grew up wanting to get the attention of both of his parents, especially his father, and prove to them that he is a good and capable man. Unfortunately, his never-ending need for attention and approval essentially becomes his downfall, which makes his character quite one-dimensional. Career-wise, he might be more successful than his brother and better paid, but just like his father, he continues to live his life through lies and deception, refuses to accept his failures, and is unable to understand his true nature. Happy represents Willy’s entitlement complex and blind ambitions.

In contrast, Biff has always been the favored son, and Willy believes that he can achieve great success in both his personal and professional life, mainly because of the fact that his oldest son was and is very popular and well-liked by many. Thus, Willy wants Biff to follow in his footsteps and become a salesman. However, Biff has no desire to become a part of the corporate world and instead prefers to work with his hands. This leads him to experience a minor identity crisis, similarly to his father, who has spent his entire life questioning and trying to define his own identity. It also makes him jump from job to job, as he constantly gets fired for his kleptomaniac tendencies. Unlike his brother, Happy, Biff accepts the reality and doesn’t delude himself. Biff represents Willy’s vulnerability and sensitivity.

In fact, this seems to be the main and most important difference between the two characters. Biff accepts the truth and even prefers it in the end, and he manages to use his potential and change, while Happy (and Willy) choose to live out their lives in delusion, blinded by their own ambitions, egos, and false sense of importance. The only things that might connect the two brothers and their personalities are their big dreams and aspirations, their blatant selfishness, and their love and support for one another.