Standard duplex refers to grades with 22% chromium, such as UNS S31803/S32205, with 2205 being the most widely used.
Super duplex is by definition a duplex stainless steel with a Pitting Resistance Equivalent Number (PREN) > 40, where PREN = %Cr + 3.3x(%Mo + 0.5x%W) + 16x%N.