Good question. Also, which R50? 96-00 have the 3.3L 170hp engine, 01-04 have the 3.5L 240hp engine.
Also, what are your purchase criteria and price point? If you're not going to use the SUV off-road a lot, and you want some "luxury" features such as heated leather seats, auto climate control, and a very comfortable ride on pavement, go with an R50. If you are looking for a rugged off-roader, the Xterra is a better choice.