Epoxy is a non cementitious product that is applied to the top of the surface. Epoxy flake floors and metallic epoxy are most commonly used. The advantage of epoxy is since it is non-porous, odor causing bacteria, grease and oils, along with other spills stay of the surface and can be cleaned easily. With epoxy, you get a much broader color and texture pallet which allows to create almost any look you may be going for.
Polish concrete is a process of grinding the existing concrete until the desired shine is achieved. Even though the surface has been polished and sealed, it is still a semonticious surface (porous). The advantage for polish concrete is the industrial look, lower cost point than most other options, and the overall durability of the floor.