Two SUVs with some similarities, but otherwise different in most aspects such as the horsepower, fuel economy, ground shadow size, and height. First of all, the 2015 Infiniti QX50 has bigger and thirstier engine; the 2016 Acura RDX gets 2.5 more mpg. And finally, the 2016 RDX body is slightly larger than the 2015 QX50, and in addition to that, it's also taller. Among similarities are the body structure, market segment, starting price, and maximum occupancy.