My two bits...
Well...From what I've seen there was the 2000 CD (Characters holding numbers), the Millenium Celebration album, a 2001 park soundtrack (Entry gate with Fab 5 and 4 logos), a relabeled Millenium Celebration CD (can't remember what they call it now), the 100 YoM CD (100 YoM artwork), and Magic in the Streets. Bear in mind I was last there in October so this info may be a bit dated. I don't have a 100 YoM CD (yet
) to compare (I think turkey leg boy is right though, I seem to remember them being VERY similar) but the Y2K and Y2K1 albums have a few differences to them.
~2K1 (100 YoM?) has some extra tracks compared to the Y2K; All Aboard!, Fortuosity, Splash Mountain Medley, Mickey's the Mouse for Me, Seize the Future (I LOVE this one), Bright Little Star, Epcot Entrance Medley (Always wanted this on CD), & Horray for Hollywood
~On the flip side of the coin the Y2K one has some that were removed from the Y2K1/100 YoM; Ev'rybody has a Laughing Place (part of Splash Mt. Medley), Canada, Finale (From Fantasmic!) (I'd rather listen to the entire soundtrack anyday IMHO), Diggin' in Dinoland (No loss. This song just drives me nuts. I'd LOVE my DAK CD except for this song), & Celebrate the Future Hand in Hand (different version from the Millenium Celebration CD)
~It's a Small World on the Y2K album is the more professional sounding orchestral version as opposed to the scratchy, LP sound from the Y2K1 version. Plus it is 1 full minute longer.
~The version of Golden Dream oon the Y2K1 album is an extended version. MUCH closer to what you actually hear in the attraction. (I, personally, LOVE the longer version)
Hope that helps some. TTFN.