Actually I haven't noticed any difference in the in-game-graphics between the AMiGA and Mac versions. But, it was a couple of months since it played it, so I might remember things wrong.
In whatever case, with Shapeshifter running on a plain A1200 with a 030 card the mac version of Sim City 2000 runs smoother than the AMiGA version does on a 060. I've managed to get the AMiGA version running on a GFX-card aswell, but that made it even slower than normal.