It depends on the model year and the make of the truck. The 2011 and newer GM/Chevy trucks are identical except for extra leaf springs on the 1-ton trucks and different cab and bed length options. With Ram the 2014 and later trucks are also virtually identical. With Ford the F-250 is different from the F-350 and the F-350 is actually part of a Ford subclass of F-350/F-450/F550 trucks.
It is too expensive to make two different models with the relatively small number of units sold. Engines, transmissions, brakes, frames, suspension members, axles and wheel bearings, are usually identical between these pickup trucks.
When you get to the F-450 and F-550 Chassis Cab versions the frames are stronger as is the front suspension and rear axle and there is a big difference in both payload and towing capacity. The F-450 pickup version actually has a lower payload rating than the F-350 pickup trucks.
