EMU is designed for city use whereas MEMU is designed for rural areas primarily. EMUs have large doors, large aisles, height of door to match platform height ( no steps present and allows one to directly get into a coach), no toilets. These features definitely helps in the easy movement of people in and out of the coaches. Whereas MEMu trains are designed in such a way that they can be boarded even from low level platforms ( common in rural areas), few long distance MEMUs have toilets, etc.