Two Pickups with more similarities, such as the body structure, starting price, height, and maximum occupancy, than differences, like the powertrain, horsepower, and ground shadow size. First of all, the 2016 GMC Sierra 3500HD Regular Cab has a more powerful engine than the 2016 Ram 1500 Quad Cab Diesel. Also, the body structure of 2016 Sierra 3500HD Regular Cab is slightly larger than that of the 2016 1500 Quad Cab Diesel. Among similarities are the body structure, starting price, height, and maximum occupancy.