Ah yes the SE-R 05-06 this was a great car, would have loved to own one new, but did not have nearly enough money at the time to buy one, anyways. The difference's first off is the engine, they both have 3.5L but the SE-R had 260HP mine has 270HP due to different friction reducing materials on the internal parts, and a think a different intake set up. Then of course the styling which was so cool. The SE-R is a much better looking Altima.