...between USP's that say USP on the handle and those that say HK USP ?
My take? Nothing, cept the mold they were made in.
My KF USPf .40 has HK USP on the left side and US pat. 5 308 815 on the right sideI believe that ALL compact models carry the HK USP designater, while only certain full size models bear the USP logo by itself irregardless of the date code.
I could be wrong..but not bloody LIKELY!! LOL!