There is a difference with 49-state emissions legal systems and 50-state (California) emissions however a USED 49-state emissions equipped vehicle, such as in the case of an out-of-state 2002 Chevy Suburban, can pass the California smog test and receive registration.
Also note, even though the vehicle is being purchased out of state, it may be California emissions complaint. Since the Underhood Emissions Label is missing, you'll need to contact the dealership and ask them to look up the vehicle's emission configuration using the VIN (vehicle identification number). It will identify whether the engine is California compliant.
Furthermore, the smog inspection for 2000 and newer vehicles consist of a visual and functional inspection of the vehicle's engine emissions system. So long as the engine's emission system has not been tampered with, the Service Engine Soon light is not on, and the emission monitors are ready, the vehicle can pass the smog test without any emissions modification; no smog parts need to be added.
Note, a new vehicle (less than 7,500 on the odometer), on the other hand, can not be registered in California if it is not California emissions certified.