The majority of the characters in Capcom Fighting Jam have been taken directly from their original games and placed in Capcom Fighting Jam untouched.
However the more observant Capcom fans will have noticed some subtle differences, below are some which I have found.
The most obvious one is that all the Street Fighter 2 characters are different from what they were in Street Fighter 2! Ryu and M.Bison use their Capcom VS Snk artwork, with some minor changes. Guile is using his Alpha3 sprite as is Zangief. Zangief's face has been redrawn and he now blows out air!
Street Fighter 3 characters have suffered badly. Not content with them losing a lot of their animation frames, they have had their palette cut drastically. However they do have some advantages as they are the only characters capable of parrying and thus are the most powerful characters in the game.
Street Fighter Alpha characters are the weakest, but they are incredibly fast and can air block. There speed can be a huge advantage when taking on the Red Earth characters.
The Red Earth characters Hauzer and Hydron were unplayable boss characters, and it shows in Capcom Fighting Jam. These characters can easily be defeated by any non-Red Earth character. All the Red Earth characters appear with reduced animation frames and palette.
The Vampire cast have survived the transition very well, they only lose their Dark Force moves from Vampire Savior.