"Subdivisions in Division I exist only in football.[6][37] In all other sports, all Division I conferences are equivalent. The subdivisions were recently given names to reflect the differing levels of football play in them.
The method by which the NCAA determines whether a school is Bowl or Championship subdivision is first by attendance numbers and then by scholarships.[38] For attendance reporting methods, the NCAA allows schools to report either total tickets sold or the number of persons in attendance at the games. They require a minimum average of 15,000 people in attendance every other year.[38] These numbers get posted to the NCAA statistics website for football each year. With the new rules starting in the 2006 season, the number of Bowl Subdivision schools could drop in the future if those schools are not able to pull in enough fans into the games. Additionally, 14 FCS schools had enough attendance to be moved up in 2012.[39] Under current NCAA rules, these schools must have an invitation from an FBS conference in order to move to FBS. Three of them—Appalachian State, Georgia Southern, and Old Dominion—began FBS transitions in 2013. All had the required FBS conference invitations, with Old Dominion joining Conference USA n 2013, and Appalachian State and Georgia Southern set to join the Sun Belt Conference in 2014." http://en.wikipedia.org/wiki/Division_I_(NCAA)