For those who don't know what Sororities or Fraternities are, here is a small breakdown on what each one means. 

Sorority - 1. A chiefly social organization of women students at a college or university, usually designated by     Greek letters 2. An association or a society of women.

Fraternity 

A group of people sharing a common profession or interests: "members of the hunting fraternity". A male students' society in a university or college. www.thefreedictionary.com