Yes there is a big difference!
From the shape they are cut in, to what they are made of.
In general, a cosmetic grade glitter is a poly-coated pigment. The plastic used is safe, even if it is swallowed or if you get it in your eye. The same is true with the pigments used that gives it color. Most craft glitters are poly coated dyes. This is different as the dyes can leach out when they come in contact with moisture. These dyes might be unsafe and cause problems. These can be harmful if you get them in the eye. Add to that the way the glitter pieces are cut is very specific in a cosmetic application. This standard means everything from how clean the cut is, the safety standards of the machine used, the containers used and even what the machine is made from. Add to that there are cosmetic standards to the packing process defined by GMP (good manufacturing procedures).