The biggest difference, of course, is that the Maxima is a front-driver; the G is RWD (unless you find an AWD version). Neither of them is especially fuel-efficient if you drive with a heavy foot. There's more room in the Maxima; the G can feel a bit snug. In my neck of the woods - your mileage may vary, of course - it's a bit easier to deal with the service counter at the Infiniti dealership than with any of the Nissan stores.