It has something to do with the frothed milk, I'm assuming... just not entirely sure.

I wouldn't know, I'm Mormon.

Starbucks definitions-

Latte- shot of espresso with steamed milk, dollop of frothy milk on top

Cappuccino- shot of espresso with 1/2 steamed milk, 1/2 frothy milk.

A dry cap is all froth-no liquid milk. A wet cap is a frothy latte.

Other places in the world it's different, cafe au lait, etc.

A cappuccino is espresso, steamed milk, and filled about half-way with foam. A latte is espresso, steamed milk, and only has a thin layer of foam on the top.