Two Pickups with some similarities, but otherwise different in most aspects such as the powertrain, horsepower, starting price, fuel economy, and maximum occupancy. First of all, the 2017 GMC Sierra 1500 Double Cab has bigger and thirstier engine; the 2017 Ram 1500 Crew Cab Diesel gets 4.5 more mpg. Also, the 2017 Sierra 1500 Double Cab is priced $8,965 lower compared to the base MSRP of the 2017 1500 Crew Cab Diesel. In addition, the Sierra 1500 Double Cab seats one more passenger than the 1500 Crew Cab Diesel. Among similarities are the body structure, ground shadow size, and height.