Oh boy, what a timely thread.
I think there's a difference between women and girls, and that doesn't have to do with age. Older ladies tend to be... womanly. They radiate that sense of matured sexuality that their younger counterparts can't quite rock. The prolonged eye contact, coy smile, subtly seductive teasing, entrancing pauses in conversation... I've known 20-year-old women with that vibe and 35+ women who don't have it. It just so happens that it takes time and experience to develop, and older ladies have generally had more time and experience.
As for "cougar hunting" - I don't see what's wrong with an older woman going to a bar to hook up with a younger guy. I see sex as a celebration of the body; if two people are up for celebrating then hey, why not. I do think it can get unhealthy when expectations are miscalculated or misrepresented but for the most part I see that situation as a harmless embrace. Women can "prey on" us young guys just as well - I prefer the term "celebrate with" though.