Most of them are visual, such as HCE's/2's lighting and shaders. But hardcore HCE players know more about the differences between the original Xbox and the gearbox PC port, especially the multiplayer part.
Made your first hot drop into HaloWaypoint.com
View your Service Record on the web.
Become a member of an active Spartan Company.
Awarded to players of Halo: Fireteam Raven.