I checked for differences in the directories on my windows 7 and my sisters mac. Macs don't have the asm, assets, blueprints, ccl_modular, compendiumunlocks, compendiumunUpdates, CustomDISkins, resourcepacks, options, stencil1, stencil2, stencil3, and usernamecache folders. I have also been told by a friend that many packs don't work on apple and he will be able to provide a list if you want one.