Didn't take long before this dropped down to a 3/4 vs 1-ton fight due to GVWR/payload huh guys?
I can't speak to the current iteration of the ford, but previous iterations the difference was basically just the sticker. Most F250s on dealer lots near me had the exact same axle, brakes, etc. as the f350s sitting next to them. For the longest time I thought they were the same minus the blocks as mentioned, and on higher payload f350s they got an overload spring.
I know for a fact the only difference between the ram 2500 and 3500 is coil vs leaf. SRW to SRW truck they are basically identical in every way. They use the same axle, although I believe the axle rating is slightly different between the two of them. Mind you, the AAM axle they use is rated at something like 11k from AAM and only 6-7k in the Ram, so there is your sign.
I know a lot of the guys on the HD truck forums, and RV forums especially, will have constant battles about the payload numbers, safety, etc. It always comes down to the discussion of "will insurance cover you in the event of something happening". From what I've seen, there are about 100 to 1 2500 trucks being overloaded on the daily, and I've never heard of someone ending up in trouble for overloading their truck. Could it happen? Sure, but you could also be held liable for an accident if you were underloaded for being negligent. Is it likely to happen? Not from what I've seen. Choose your risk and go with it. Add airbags if it makes you feel better, or upgrade your brakes.
As for overloading midsize trucks vs HD trucks. I honestly think the vast majority of midsize truck guys don't know what payload even is. Especially with the Jeep and Taco crowd it's about how many cool aftermarket off road accessories you can slap on your truck that matters. One of the consistent upgrades I see is guys upgrading their springs to better support the weight, upgraded brakes, etc. So they are taking the weak parts and upgrading them to make them more stable, better able to stop, etc.
Payload numbers for most midsize trucks are pretty small, but I think it's mostly a classification thing, not a engineering thing.
It's also pretty crazy how up in arms some people get about payload numbers. By the letter of the law, you can upgrade your 1 ton truck with super light springs, toss a roof rack and overload the rack way up top and be a-ok legally. However, going over the payload numbers, even if you're keeping weight down low, or upgrading the suspension and brakes to better handle it, is somehow not ok.