According to Edmunds.com, a 200SX weighs 2330 lbs, while a Sentra weighs 2377 lbs. Not much of a difference between the two, but there's still a little bit. I took these off of the 96 200SX SE, and 96 GXE...so there might be minor differences when it comes to certain models and years.
Check using the weights listed on the door. Subtract one from the other and you'll get your actual weight. My B14 sentra comes out to 2600lbs. Those edmunds specs seem too optimistic, at least for the B14 chassis.