Lady Macbeth and Macbeth are both ambitious, but Lady Macbeth is more persistent and Macbeth is more impulsive.
In the beginning of the play, Macbeth is an honorable and brave solider. He stands up to Macdonwald, the traitor. He fought through a battle like “valor’s minion” (enotes etext pdf p. 9). Duncan greets Macbeth like a friend and cousin, and a loyal subject. Unfortunately, Macbeth gets interested in higher ambitions when the witches tell him he will be Thane of Cawdor and then king. When he gets the first promotion, he expects the second.
Stars, hide your fires;
Let not light see my black and deep desires:
The eye wink at the hand; yet let that be
Which the eye fears, when it is done, to see.(60) (p. 18)
Macbeth may be ambitious, but he has more thought than action. Lady Macbeth is the one with the action. She is persistent enough to continue whittling away at Macbeth, urging him on. She tells her husband to pretend to be nice to Duncan while plotting against him, so he won’t be suspicious.
Your hand, your tongue; look like the innocent flower,(70)
But be the serpent under't. (p. 20)
When he seems to waver, she basically calls him a wimp.
But screw your courage to the sticking-place,
And we'll not fail.(p. 24)
Lady Macbeth urges Macbeth to the specifics of the murder, and he does become king. However, she has created a monster. She cannot control him afterward, because Macbeth is more impulsive. He begins killing and killing, and seeing imaginary daggers and ghosts. She realizes that he has lost it, and she cannot control him anymore. Eventually, she loses her mind and kills herself out of guilt.
Macbeth also succumbs to guilt, but he is more impulsive. He fights to the last minute, thinking he cannot die, until he finds out that Macduff really can kill him. Then he gives up.