I don't think there's necessarily any physical differences in bodily functions, but you will learn very quickly that there is a HUGE cultural difference. Men don't give two s***s about letting out a big subwoofer-worthy racket when they do it, while women are sometimes too discrete to even go #2 in a public bathroom, (look up "poop standoffs." Yes, they happen.) Or if they do, they make a special effort to do it as quietly as possible.
I don't think it's physical, it's just cultural. Men: "who cares, get out of my way," Women: "sorry for taking up too much space, and sorry for making too much noise, and sorry for making anyone else uncomfortable."