The 38 Super is an old design. It is semi-rimmed and very popular with the IPSC/IDPA crowd. In fact, my carry gun is a Super.
The 9x23 is a newer design. It is a 9x19 on steroids. The case web is thicker and it’s designed to handle higher pressures. It hasn’t caught on as well as I though it would have.
Both shoot .355 diameter bullets, some older super barrels are .356 though. Both are fine calibers.
AF Shooting Team