Unbaked, FIMO Decorating Gel looks clear, transparent and the viscosity is thin whereas Kato and TLS are rather opaque, white and the viscosity is thick. When baked, FIMO is clear, shiny and has some flexibility. The Sculpey and Kato stay a little cloudy, have a matte finish and expand a little while baking. Of course, the translucent quality of any liquid clay depends the thickness of the application or the type of material you add to it such as, metallic powders, paint or glitter.
To learn more about these products, see them used and the results of their qualities that were tested, check out these web sites: