Guys…that are two different things.
example,
Generator set with 0.8 power factor mean:
alternator unit will be in kVA with engine unit will be in kW with factor 0.8 (not the alternator)
at the load side, power factor is kW/kVA which is a composite of power factor
the composite power factor at the load side are possible to be corrected but generator (set) power factor cannot be corrected unless by changing the engine capacity or alternator capacity.
hope the above could helps you