Two Minivans with more similarities, such as the body structure, starting price, ground shadow size, height, and maximum occupancy, than differences, like the model year, horsepower, and fuel economy. First of all, the 2016 Sienna has a more powerful engine and gets 1.5 mpg less than the 2013 Odyssey. Among similarities are the body structure, starting price, ground shadow size, height, and maximum occupancy.