The 23 levels of the PlayStation version were reduced to only 12. This removed the factory levels where Pac-Man rescues Pac Jr. and this reduction in levels also causes the majority of the boss fights to be removed too.
The Maze Mode and Classic Mode of the PlayStation version are not present here.
The story told through FMV cutscenes of the PlayStation version are now just still images with text. Since the FMV's were removed the bonus outtake FMV's that were rewarded for players who collected all the P-A-C-M-A-N letters are not here with collecting the letters now simply counting to the completion percentage of the game.
No hub worlds at all unlike the PlayStation version which had them.