Although there are some similarities, these two are different in most aspects such as body structure, horsepower, ground shadow size, and maximum occupancy. First of all, there is a significant difference between body structures and exterior dimensions. The 2016 GMC Sierra 2500HD Double Cab is a Pickup, while the 2015 Mercedes-Benz Sprinter is a Van. It is also slightly smaller. Also, the 2016 Sierra 2500HD Double Cab has a more powerful engine than the 2015 Sprinter. And finally, the Sprinter seats two more passengers than the Sierra 2500HD Double Cab. Among similarities is the starting price.