Espero que ajude:
"Full-Towers support Full ATX and most of the time Micro as well
Mid-Towers support Micro ATX
Mini-Towers support Baby ATX boards, these boards come ussually with only 1 expansion slot vs Micro ATX which can come with ussually 3 Ex Slots. The case itself cannot support Micro ATX or Higher form factors.
As far as bays go, you get a ussual amount of 4cd+2 floppy with Full-Towers, 2cd+1 floppy with Mid-Towers, and 1cd bay with mini-Towers "
fonte:
http://forums.hardwaresecrets.com/exactly-differences-mini/2361?