Future is, as already stated, acrylic BASED (mesning it is essentially a clear acrylic). The different manufacturer clear gloss acrylics are, more or less, pure acrylic, but will acheive the same effect. The benefit from using Futer is that it cost so much less, by volume, so you can put some in a container, dip the clear part(s), and either save or dispose the Future. I've used both Future and the Testors, for different things, and think that both are important.
I have used Future to make instrument bezels on a model or two, and haven't used Testor's for the same thing, but they should work for that also. They are, insofar as model building goes, interchangeable. Want to diip the parts (say, an auto windshield)? Use Future. Want to use it in an AB or brush it on, or gloss an area for decals? Use either one.
My opinions and experiences.
Michael
We could change the world, but God won't give us the source code!