Two Pickups with more similarities, such as the body structure, starting price, ground shadow size, height, and maximum occupancy, than differences, like the powertrain and horsepower. First of all, the 2016 Ram 2500 Mega Cab has a more powerful engine than the 2016 Nissan Titan XD Diesel. Among similarities are the body structure, starting price, ground shadow size, height, and maximum occupancy.