Lady Macbeth and the witches both manipulate Macbeth, but while the witches are just playing around and putting ideas in his head, Lady Macbeth gives him specific plans and basically forces him to commit murder.
Although the witches are definitely vile creatures who like to stir up trouble, they only tell Macbeth that he will be king. They do not tell him to go out and kill Duncan straight away to make it happen. Lady Macbeth does that. The witches plant a seed, and Lady Macbeth nurtures it and makes it grow.
All hail, Macbeth, that shalt be King hereafter! (Act 1, Scene 3, p. 13)
When Duncan does not name Macbeth as the next king, he gets angry. He never thought he would be king before, but since the witches have put the idea in his head he wants it.
[Aside.] The Prince of Cumberland! That is a step(55)
On which I must fall down, or else o'erleap,
For in my way it lies. (Act 1, Scene 5, p. 18)
Now Macbeth is interested in becoming king, and when he sends a letter to Lady Macbeth she is ready to make it happen. She gives him a specific plan, and makes sure he follows it to the letter—right down to leaving the daggers by Duncan’s body.
Go, get some water
And wash this filthy witness from your hand.(60)
Why did you bring these daggers from the place?
They must lie there. Go carry them, and smear
The sleepy grooms with blood. (Act 2, Scene II, p. 30)
In the end, it is Lady Macbeth’s insistence that her husband act that causes him to act, more than the witches’ giving him the idea.