Two Pickups with more similarities, such as the body structure, powertrain, starting price, ground shadow size, height, and maximum occupancy, than differences, like the horsepower and fuel economy. And finally, the 2017 Nissan Titan XD Regular Cab Diesel has bigger and thirstier engine; the 2017 Ram 1500 Quad Cab Diesel gets 3 more mpg. Among similarities are the body structure, powertrain, starting price, ground shadow size, height, and maximum occupancy.