I see it posted often in the truck camper section about someone buying a gasser instead of diesel to get more payload, yet the rear weighs the same on both configurations of the same truck, so the payload difference is due to the limit on GVWR in that Class of truck and not due to capacity.
My F250 came with the standard 17" wheels that were rated lower than the optional 18" - The F350 of that era came with the higher rated 18's as stock. I was able to buy a new set of dealer take-off mounted 18's for less than just replacing my 17" tires, so I now owned a F250 with OEM optional suspension and tires that was identical to a F350 except for the badging and 2" lower rear axle block. In current models, there is more is more difference between the two Ford trucks but not really that much.