We have no idea why a vehicle maker comes up with numbers like GVWR/FAWR/RAWR/GCWR/CCC/Payload based on a gvwr/tow ratings/etc.
Some (not all) 4x4 pickups have higher payloads than a same 2wd truck.
I would say with out actual mechanical specs to look at for each vehicle it would be just a guess to assume the two vehicles in question are the same or different.
Exception is Fleet Ford specs that has the actual different specs for the F150....F250....F350 SRW ... F350 DRW pickups. Ram and GM mechanical specs aren't that easy for the lay person to find.