The biggest difference between men's and women's wrestling is the utter lack of Division-I teams for women. Also, only twenty-four colleges have a varsity team for women. As people get more used to the idea of women participating in combat sports, this might change. Emphasis on the "might" (source).

Men's wrestling is subdivided into two different kinds: "freestyle" and "Greco-Roman." While the latter sounds like it's done naked, it's totally not. Greco-Roman matches begin standing up, while freestyle matches are on the mat. Women only wrestle freestyle, likely because the Ancient Greeks and the Romans weren't fans of women doing pretty much anything. 

"No girls allowed, right Flavius? I said right, Flavius?'" "Please, just let me go."

Weight classes are also slightly different. It should come as no shock that men and women tend to be different sizes, and the weight classes reflect this. It's important to note that while weight classes are presented as ranges, they're actually discrete numbers, and you should often try to get as close to the maximum for your range without going over. 

It's like Blackjack, but instead of busting, you'll get thrown out of a match. For men, the weights range from 125 pounds all the way up to 285. For women, it's from 105 to 200 pounds.