Two Pickups with more similarities, such as the body structure, starting price, ground shadow size, and maximum occupancy, than differences, like the horsepower, fuel economy, and height. First of all, the 2018 Ram 1500 Crew Cab has bigger and thirstier engine; the 2018 GMC Sierra 1500 Crew Cab gets 1 more mpg. And finally, the 2018 Sierra 1500 Crew Cab has a slightly taller body than the 2018 1500 Crew Cab. Among similarities are the body structure, starting price, ground shadow size, and maximum occupancy.