The only difference is the program inside. The Buell "Race ECM" is identical in every way to a regular Buell ECM.
To make matters more muddy, the Buell ECM's were jail-broken many many moons ago, meaning there is no telling what fuel map is in what ECM, including buying a "Race ECM" from an unknown source.
History lesson aside, if you want to purchase a plug-n-play ECM with the "Race program" in it, get one from IDSpd.com. If you want to put the Race program into yours, by yourself, go to Rev-Mo.com