Mac Lemmings has, I am pretty sure, close to exactly the same level data as the Amiga version, except that levels with 100 lemmings have 80 instead. However, there are significant gameplay differences, most notably:
* The Mac's clock runs really slow (lemmings can walk much further in one game second), whereas Amiga is one of the fastest versions. This can be seen most dramatically on Mayhem 16 (Just a Minute) where, on the Mac, you can just dig and start bashing the wall with the first lemming, set the RR to 99, and easily finish in time.
* The Mac has hi-res terrain but low-res physics, and the solidity of the terrain pieces doesn't always match the solidity of the Amiga/DOS low-res terrain. Most notably, on Mayhem 26 (The Steel Mines of Kessel), the lemmings can't pass three of the "thorns" on the downward slope before the trap, so extra bombers or builders are required to get past them. Combined with only being able to lose 8 lemmings (because the level has a save requirement of 90%, and 80 lemmings instead of 100), this makes it one of the hardest levels in any official Lemmings game.
* Tricky 21 (All the 6's) is replaced with a completely different level, Going Their Separate Ways.
