The main differences between the two are a sport-tuned suspension, those 19-inch machined alloy wheels and tires, distinctive headlights with dark chrome inserts, and R-Spec badges outside the vehicle and on the floor mats.
There's the 2002 Nissan Spec-V Sentra SE-R, which, idiotic name aside, is a screaming pavement ripper loaded with all sorts of suspension and engine refinements to make it a blast in any bend.