In Shakespeare's Macbeth, Macbeth exhibits remorse and guilt for the murder of King Duncan, but remorselessly denies any guilt for the murder of Banquo. The unnamed narrator in Edgar Allan Poe's The Tell-Tale Heart exhibits no guilt whatsoever, but exhibits irrational, debilitating fear associated with the possible discovery of his murder of the old man.
Macbeth murders King Duncan, and, in act 2, scene 2, he returns to Lady Macbeth, clearly unnerved by what he's done.
MACBETH. I have done the deed. ....
This is a sorry sight. (2.2.18, 28)
Lady Macbeth tries to calm him, but Macbeth can't get the murder out of his head. To take his mind off what he's done, Lady Macbeth tells him to "Go, get some water / And wash this filthy witness from your hand" (2.2.59-60). Then she notices that Macbeth left the murder of Duncan unfinished.
LADY MACBETH. Why did you bring these daggers from the place?
They must lie there. Go carry them, and smear
The sleepy grooms with blood.
MACBETH. I'll go no more:
I am afraid to think what I have done;
Look on't again I dare not. (2.2.61-66)
Macbeth is clearly feeling guilty and remorseful for having murdered Duncan, but it's equally clear that Lady Macbeth feels no remorse or guilt whatsoever for her part in the murder. Instead, she hopes to transfer the guilt for Duncan's murder to Duncan's guards.
LADY MACBETH. Give me the daggers.
...If he do bleed,
I'll gild the faces of the grooms withal,
For it must seem their guilt. (2.2. 67-72).
At no time leading up to his murder of the old man does the narrator of The Tell-Tale Heart express any second thoughts about what he's planning to do. He does remark, "I loved the old man," but immediately preceding that remark he flatly states "Passion there was none" regarding the intended murder. He feels no emotions at all about the murder except for his obsession with killing the old man to relieve himself of the old man's "evil eye."
"I made up my mind to take the life of the old man, and thus rid myself of the eye forever."
The narrator explains his behavior and his thought process in preparing for the murder. He notes, "I was never kinder to the old man than during the whole week before I killed him," but the narrator treats the old man with kindness not because he feels regret or remorse for what he's about to do, but because he doesn't want the old man to suspect what he's planning.
At the end of their scene after Macbeth's murder of Duncan, Macbeth and Lady Macbeth hear knocking at the castle door. Macbeth is frightened at the sound, and stands motionless, not knowing what to do. Lady Macbeth urges him to go with her to their chambers so they can wash the blood from their hands and prepare for their visitors.
LADY MACBETH. Get on your nightgown, lest occasion call us
And show us to be watchers. Be not lost
So poorly in your thoughts.
MACBETH. To know my deed, ’twere best not know myself.
Wake Duncan with thy knocking! I would thou couldst! (2.2.89-93)
Macbeth is feeling guilt and remorse for Duncan's death, and wishes he would never have murdered him. From that point in the play, however, Macbeth puts aside any regrets he has about killing Duncan, and joins with Lady Macbeth in their efforts to conceal their part in Duncan's murder.
In The Tell-Tale Heart, the narrator seems almost giddy in the way he explains how he planned and executed the murder of the old man.
When the narrator makes a sound that wakes the old man, and the old sits up in bed, listening to the night sounds, the narrator seems to empathize with the old man, but the seeming empathy turns to self-satisfaction.
Many a night, just at midnight, when all the world slept, it has welled up from my own bosom, deepening, with its dreadful echo, the terrors that distracted me. I say I knew it well. I knew what the old man felt, and pitied him, although I chuckled at heart.
The narrator's self-satisfaction, self-obsession, and absolute lack of any sense of guilt or remorse is further exemplified in his explanation of what he did after he murdered the old man.
When I had made an end of these labors, it was four o'clock—still dark as midnight. As the bell sounded the hour, there came a knocking at the street door. I went down to open it with a light heart,—for what had I now to fear?
The self-congratulating, light-hearted narrator is firmly convinced that the murder will never be discovered.
When the ghost of Banquo appears at Macbeth's coronation banquet in act 3, scene 4, Macbeth refuses to accept guilt for Banquo's murder.
MACBETH. Thou canst not say I did it: never shake
Thy gory locks at me. (3.4.62-63)
Macbeth is relying on a technicality. Macbeth ordered the death of Banquo, but he didn't actually commit the murder himself.
Macbeth further disavows any responsibility for the murder of Banquo, as well as for the murders he intends to commit in the future, by rationalizing that he's only committing these murders to protect himself. He further justifies his actions by saying the he's so deep into his situation that there's no use trying to extricate himself from it, and he might as well do whatever he needs to do to stay alive and remain King.
MACBETH. For mine own good
All causes shall give way. I am in blood
Stepp'd in so far that, should I wade no more,
Returning were as tedious as go o'er... (3.4.164-167)
The narrator in The Tell-Tale Heart becomes increasingly paranoid and irrationally fearful that his murder of the old man will be discovered by the two policeman who've come to investigate a report made by a neighbor about a shriek coming from the narrator's home. When he finally confesses to the murder, the narrator blames the two policeman and the beating heart that only he can hear for his confession.
“Villains!” I shrieked, “dissemble no more! I admit the deed!—tear up the planks! here, here!—It is the beating of his hideous heart!”
"I admit the deed!" he says, but he expresses no guilt or regret for the murder.
Near the end of Macbeth, after Macbeth is told that Lady Macbeth is dead, Macbeth seems to resign himself completely to his situation. He seems also to relieve himself of any guilt, regret, remorse, or responsibility for whatever he's done to become and remain King, and he essentially absolves himself of the murders of King Duncan, Banquo, and Macduff's wife, children and servants.
MACBETH. Life's but a walking shadow, a poor player
That struts and frets his hour upon the stage
And then is heard no more. It is a tale
Told by an idiot, full of sound and fury,
Signifying nothing. (5.5.26-30)