Mr. Brewski,
Rasho plays much better positional defense and is quicker to rotate over on switches/help. He's had 2 years in the system and Nazr isn't close to Rasho in understanding, experience, nor reaction time - yet.
Rasho is a better passer in the high post and so far, a better shooter out on the floor. He is much smoother in the two-man game on screen/rolls and his screens are technically better than Nazr's.
Nazr dunks and is more aggressive on the offensive glass and has a knack for offensive rebounding. Nazr is more physical. Nazr is Rasho's backup until he starts catching balls on the first attempt and his familiarity and reaction time improves. On defense, Nazr is "Captain Late, Jr." but that's meant in the help-D sense and not in the 4th quarter heroics sense.