GPS leaves behind protection, Hyper Polish won't. Hyper Polish is pretty mild IMO, depending on the pad used, but if you don't need any correction something like Optimum Finish, or even just a Pre-Wax cleaner will work better. GPS is a great all in one BTW, but if you plan to use a dedicated wax or sealant it makes more sense to use something with no protection in it.
Yes, Hyper Polish has abrasives, as does GPS if I recall correctly.
Just my $.02