Super 31 an J32 are the same aircraft. It was marketed as the Super 31 in the states.
J31 = 940 SHP TPE 331-10 engines
J32 = 1020 TPE 331-12 engines
J32 has higher operating weights, better range , faster (232 KT v 223 for a 31.)
J32EP is an enhanced performance version with areodynamic mods on the nacelles, better brakes and a redefined ground idle blade position to make better use of the range of prop thrust available.
Hope this info is of some use.
J31 MAN