Whats the difference between a “sorority” and a “womens fraternity?

The words fraternity and sorority are used interchangeably for women’s Greek-letter groups. Fraternity is derived from the Greek word “phrater,” meaning brother, sister, or clan. “Soror,” the source word for sorority, is Latin and means sister. The word “sorority” did not come into usage until the late 1800s and groups founded prior to then are officially incorporated as women’s fraternities. Today the term “sorority” is used to distinguish women’s groups from men’s groups.