In Harper Lee's To Kill a Mockingbird, comparing Atticus Finch to Bob Ewell is like comparing God to the devil. No two characters that I can think of are so diametrically opposed.
Atticus is a man of integrity. His moral compass not only guides his actions, including his respect for the dignity of others, but it keeps him grounded as he tries to guide his children in a sometimes-ugly, and often changing world. Atticus is humble and respectful of everyone, even Bob Ewell. He refrains from speaking badly of anyone, and he believes that people should assume responsibility to help the world, as well responsibility for their actions. Atticus tells the children that before they judge, they need to walk around in someone else's skin for a while; in this way they better understand others and themselves. Atticus is very concerned that his children will always be able look to him for guidance and with respect—something he expects he must earn. He believes, too, in protecting the weak: the mockingbirds—which include Boo Radley and Tom Robinson.
Bob Ewell, on the other hand, is a poor excuse for a human being. He does not care for his children: he is abusive and sees to his need for alcohol before his children's need for food or clothing. He is vulgar and crass, as we see in the courtroom. He is a liar and a bigot, with no respect for the truth or for other people. He does not work, but the money he gets on "assistance" he drinks away. He is not interested in setting an example for his children, as we see with Burris Ewell when Scout starts school. Bob is a bully and would-be murderer.
Sheriff Tate shares his opinion of Bob Ewell with Atticus stating that there are some people that should just be shot and done with it, and one of those people is Bob Ewell.
There could hardly be two more contrasting characters in any single piece of literature than Atticus Finch and Bob Ewell. Bob is the virtual antithesis of Atticus, and the contrasts are practically endless.
- Atticus is a successful lawyer, and Bob is unemployed.
- Atticus is an intelligent man, and Bob is totally uneducated, barely able to write his name.
- Atticus is a sincere parent, who takes care of his children. Bob lets Mayella take care of the parenting.
- Atticus sees that his children get a good education, while Bob lets his kids go to school on the first day only--filthy and disrespectful.
- Atticus is honest and friendly; Bob is dishonest and hateful.
- Atticus is sober; Bob is a drunk.
- Atticus is a friend of Maycomb's black populace, while Bob hates black people.
- Atticus threatens to spank his children, but never has; Bob beats Mayella, possibly on a regular basis.
- Atticus provides a nice home for his family on a residential street; Bob's ramshackle house is on the edge of the dump.
- Atticus is tall; Bob is short.
- Atticus is passive; Bob is a bully.
Perhaps their only comparisons are that both men are widows and both live in Maycomb (and are probably native Alabamans). Otherwise, no two men could be more different.