Lady Macbeth is not as reluctant to kill the king as Macbeth. She says to herself that Macbeth is "...Too full of the milk of human kindness to catch the nearest way."(1.5.14-16) In this she means that Macbeth if too kind to act on his ambition.
As for her husband, Macbeth was loyal and ready to go head first for the king. "For brave Macbeth—well he deserves that name—Disdaining fortune, with his brandished steel, Which smoked with bloody execution, Like valor’s minion carved out his passage" (1.2.16-19), this quote is from the captain telling King Duncan about how Macbeth is fighting killing all the enemies in front of him. Just this act alone makes King Duncan deem Macbeth as the new Thane of Cawdor.
Even Lady Macbeth' s nerves are getting to her at least a little bit because of their plan to kill Duncan, so she drinks her nerves away. "That which hath made them drunk hath made me bold. What hath quenched them hath given me fire" (2.2.1-4).
As for Macbeth, he is full of guilt and can't believe what he has done. After killing Duncan Macbeth says, "How is’t with me when every noise appals me? What hands are here? Ha! They pluck out mine eyes. Will all great Neptune’s ocean wash this blood Clean from my hand? No, this my hand will rather The multitudinous seas incarnadine, Making the green one red (2.2.56-62). This show how Macbeth, even though the blood washes off, knows that the guilt is still there.
Even after Duncan' murder and Macbeth becomes king, Lady Macbeth seems oddly calm and collective about their recent deeds. However she is worrisome for her husband's grief. "Naught's had, all's spent, where our desire is got without content. 'Tis safer to be that which we destroy than by destruction dwell in doubtful joy." (3.2.6-11) Meaning, there is no point in getting what you want if you can't enjoy it. You'd be better off dead.
Her Husband, Macbeth, now sees that he is in too deep and going to kill anyone who is a threat. Macbeth says, "...I am in blood Stepped in so far that, should I wade no more, Returning were as tedious as go o'er. Strange things I have in head, that will to hand, Which must be acted ere they may be scanned (3.4.136-140). In this Macbeth sees that there's is no point of returning to his once peaceful life. He has to continue to trudge on in his new chaotic world.
Even if she hides it well, Lady Macbeth's conscience cannot escape her guilt. "Out, damned spot! Out I say!...Hell is murky! Fie, my lord, Fie! A soldier, and afeared? What need we fear who knows it, when none can call our power to account? Yet who would have thought the old man to have had so much blood in him." (5.1.31-35)
After hearing the prophecy Macbeth believes he could never be overthrown. "...Rebellious dead, rise never till the wood Of Birnam rise, and our high-placed Macbeth Shall live the lease of nature, pay his breath To time and mortal custom..." (4.1.101-105). At this Point Macbeth is full of himself and is willing to do anything he wants without the fear of death.
In this scene the nurse and the doctor are observing Lady Macbeth as she is sleep walking and her guilt begins to come out in admission from her sleep talking. "The thane of Fife had a wife. Where is she now? What, will these hands ne'er be clean? No more o' that, my lord, no more o' that! You mar all with this starting." (5.1.37-39)
Macbeth now doesn't have a friend in the world, and everyone dislike and fears him. Angus says, "Now does he feel His secret murders sticking on his hands. Now minutely revolts upbraid his faith-breach. Those he commands move only in command, Nothing in love. Now does he feel his title Hang loose about him, like a giant’s robe Upon a dwarfish thief" (5.2.17-22). This quote explains how terrible and warped Macbeth personality has become. From his once caring nature to his now ruthless manner.