So I'm pretty sure that's the difference between GVWR and GCWR
The gross combined rating is everything that engine can pull and the brakes can stop with.
Good engine and gear will get the load moving.
But payload is allll about GVWR. What's the lightest most stripped down truck riding on the suspension, with the most room under the Maximum weight of the GVWR.
That might be a stripped down V6 with stiff springs.
Example from autoblog
penned by tech hipsters who can be preachy millennials.
The dinky minitruck with its tiny engine, has stiff springs and makes it under the GVWR.
The loaded up F-150 has hundreds of pounds of options on it.
The Ford is VASTLY better truck to live in, way more capable in terms of towing, and you won't miss the theoretical gap in payload - as the F-150 would likely be better experience with the equivalent load.
The payload vs options thing is across brands.
Many a truck buyer has ordered out a fully optioned diesel F-250 platinum, and been shocked to find the payload is 1,900lbs.
They figured, the engine is shockingly powerful, doesn't that give it more payload? well it will accelerate no problem at all, but payload is a factor of a few things, and that big diesel engine is very heavy.
The stripped down contractor grade 6.2L V8 F-250 had a payload of 2,800lbs.