I'm guessing you didn't see him play in college.
You want to talk about the NBA, then yeah, Dominique Wilkins was vastly superior. In college? Williamson had a far bigger impact, on much, much, much better teams. In Dominique Wilkins 3 years at Georgia, they went 52-37 and never played in the NCAA Tournament. In Corliss Williamson's 3 years at Arkansas, they went 85-19, and won 13 NCAA Tournament games- with him as the obvious best player on the team all 3 years.
Williamson was a 6'7" low-post beast, which simply didn't translate into the NBA. Wilkins' game, transferred into a league where zone defense and double-teaming were basically outlawed, got vastly better. In college, though, it was Williamson who was the 2 time AA, 2 time SEC POY, and MOP of the 1994 FF.