SU-100 assault gun, SU-85 and SU-100 tank destroyers

The SU-122 was a self-propelled 122mm gun produced on the chassis of the T-34 Medium Tank, and was similar in concept to the early versions of the German StuG, designed to provide close support for the infantry
The SU-85 was a Soviet tank destroyer based on the SU-122 assault gun, which was itself built on the chassis of the T-34 Medium Tank.
The SU-100 was a Soviet tank destroyer developed as an up-gunned version of the SU-85 after the 85mm gun used in that vehicle was installed in the T-34-85.