These two Cadillac CTS models are two modifications of the same model with one major difference, the modifications. First of all, the 2015 Cadillac CTS Vsport is more fuel efficient; it gets 1 more mpg than the 2016 Cadillac CTS V-Sport. Among similarities are the body structure, market segment, starting price, horsepower, ground shadow size, height, and maximum occupancy.