Assuming that you are looking at the pickup version of the F450 with a crew cab the factory specs are 0.6" higher in 4wd and 2.3" higher in the 2wd versions.
Ford super-duty truck specs"Anxiously waiting for responses. Thought of the F450 for a 3 slide truck camper."
The F450 turns sharper due to having the wider front end but in the pickup version it actually is rated to carry less. The pickup version is tailored for trailer pulling, not for weight carrying. So it is a toss-up as to which one would be better suited for a slide in. If you want to go with a flat bed all of that changes. You can see the details here:
2020 Ford towing guide