The Alliance of American Football was an upstart football league made up of a number of NFL veterans, including some as pedigreed and as established as Bill Polian, a member of the Pro Football Hall of Fame as an executive. The XFL is the pet project of Vince McMahon, the owner of World Wrestling Entertainment, a league that already failed once nearly two decades ago.
The AAF has ostensibly learned from the failure of the XFL and of all the upstart leagues to come before it. It was the most serious attempt to bring forth a rival football league since the XFL.