Granted, this linked style/performance analysis is a bit hard to compare across considering length of service, quality of the competition, etc. See the link below to Statsheet. Please note, these stats do not include the 2008 season yet in their database. For the record, Lowery's winning % has dropped to 70.1, McKillop's went up slightly to 60.2 (now with some NCAA wins) and Brownell's is now 67.9.
Summary
Buzz and McKillop's teams score more (the opposite side is that Brownell and Lowery are more defensive minded). McKillop's teams rebound better, but have more turnovers. Buzz's team shot better (including treys) and turned the ball over less.
Not definitive, but can give us a glimpse of what to expect of the four.
http://statsheet.com/mcb/coaches/compare?i=1&add=bob-mckillop&c1=brad-brownell&c2=buzz-williams&c3=chris-lowery