Two Pickups with more similarities, such as the body structure, starting price, ground shadow size, and maximum occupancy, than differences, like the horsepower and height. First of all, the 2017 Ram 2500 Regular Cab has a more powerful engine than the 2017 GMC Sierra 2500HD Regular Cab. And finally, the 2017 Sierra 2500HD Regular Cab is slightly taller than the 2017 2500 Regular Cab. Among similarities are the body structure, starting price, ground shadow size, and maximum occupancy.