As far as i know, the SE-R came with a unique "wing" on the back, and a different, 5-spoke style wheel. the suspension also featured larger anti-roll bars
the major difference, although not so obvious from a distance, is the engine. If you are looking at the engine from the front, on the passenger side of the hood is a sticker that has the words Catalyst, and the Nissan logo. next to those, it should say SR20DE. if it doesnt say that, it isnt an SE-R. all other B13 featured the GA16DE,which is still a good engine, but does not have the aftermarket support of the SR20DE
Engine Code
Wheel
Wing
Hope that answers your question.