These two surprisingly have more similarities, such as starting price and ground shadow size, than difference, like body structure, maximum occupancy, and horsepower. First of all, despite the fact that the 2017 Chevrolet Silverado 3500HD Regular Cab is a Pickup and the 2017 Ram Promaster Window is a Van, there is no major difference in exterior dimensions. Also, the 2017 Silverado 3500HD Regular Cab pulls more horsepower than the 2017 Promaster Window Van. And finally, you'll seat four more passengers in the Silverado 3500HD Regular Cab than in the Promaster Window Van. Among similarities are the starting price and ground shadow size.