The second version has heard about the clitoris, but have absolutely no idea where it actually is. Is it somewhere near the bellybutton? Is it to the right of your labia? Is it actually inside the vagina somewhere? These people will put their hands lots of places, but none of it will be on the clitoris. Sometimes they might actually luck out and find it, but at that point it's like not seeing the forest for the trees.
Third version knows exactly where the clitoris is, but has no idea what to do with it. Do you just sort of...poke it? Do you begin by furiously rubbing it and ignore all other parts of the vulva? Who the hell knows. But hey, you found it! So that counts for something.
For awesome stuff about the clitoris, I direct you here.