Actually, no. A Kommando is a specialty ork that makes good use of ambushes and unexpected attacks. http://wh40k.lexicanum.com/wiki/Kommandos

Nobs are basically just under a warboss in terms of rank. The only real differences with nobs would be Meganobs (Which are nobs in mega armor, which I thought might be a little unfair) and nob warbikers, which is closer to my nob. But for all intents and purposes he is a standard nob.