Totally different products and purposes.
Rage is a very popular polyester based body filler for used cars. It is wiped on as a thixotropic solid, most commonly to fill a dent.
PPG JP202 is a urethane high build primer-surfacer. It's sprayed on and block sanded back off as the last step before paint, for optical surface flatness.
I use Rage in some applications, but not on my airplane fiberglass or aluminum. Cheap, fast, good, pick any two. Epoxy/micro has better adhesion, but it's not fast.
Generally, urethane primer surfacers are pretty good, and I like PPG products. Shopline is a lower end PPG product, I suspect better than most budget brands.