"Sculpey 2" or "Super Sculpey" is a second-generation sculpey. It is a tannish neutral tone, it is softer, less crumbly, is easier to get started (sculpey you have to kneed forever to get it pliable). Sculpey 2 also sands, scrapes, finishes, and paints more smoothly than its ancestor.
Colored Sculpey--Sculpey III--is also available in 44 different colors, although it's pretty much just standard fimo clay, no better or worse.
The main advantage sculpey has over most sculpting mediums is that it *can* be baked in a standard home oven, so projects can be done entirely in the home, with no need for a kiln. Really good for school craft projects.