I definitely agree with what Footprints has to say about people being different, and on some of the specifics of what may differ...

(And here's another) However..

"And she will not necessarily contract when she comes."

Yes, she will; everyone (with normal anatomy) has muscular contractions when they have an orgasm. It is part of the biological definition of an orgasm; it is a necessary condition to define something as an orgasm. If she's a-moanin' and a-groanin' but isn't contracting, she may be having a good time but not actually coming, or she might be faking an orgasm. I'm not going to say everyone has contractions in the same way, but, barring major physiological differences, it's pretty darn close.