Question: is ii lens vs stm lens?
Answer: In general STM lenses have quieter and smoother focus than their non-STM counterparts, especially compared to USM lenses. ... In the case of the EF-S 18-55mm f/3.5-5.6 IS II and the EF-S 18-55mm f/3.5-5.6 STM though, the STM is also slightly faster to focus than the older IS II.