What on earth is the deal with foundation, the first layer in any woman's make-up routine?

I was in The Body Shop the other day with Dawn, and she was trying to decide whether to buy a different kind of foundation or not, as they didn't have her regular one in. So as we are stood there, the sales assistant comes up, and shows Dawn a couple of them.

“This one goes on as a powder and gives a smooth finish, and this one goes on as a smooth cream, and gives a powdery finish.”

You what? Did my man ears hear correctly? They've spent time and money developing foundation to look like the opposite of how it is applied, both ways! Madness. Why? Why why why why why? It simply does not compute in my man brain why they needed to do this. What is the point! Maybe it is a good sign I don't understand it, maybe I should ask this question on Yahoo! Answers. I shall update you if I get an answer, meanwhile feel free to hypothesise in the comments.

Update! People have answered my question!