The SFT is very similar to the NXT but there are a few differences.
The SFT has a bounce beam eye, the NXT is break beam.
The NXT has slightly stronger feedneck threads. Not a big deal as I've not seen an SFTs break.
Better trigger and frame on the NXT
The SFT does not come stock with a Q-lock, HE bolt kit etc that came stock on the NXT.
The SFT is lighter than the NXT and if it is an 05/06 comes with a better solinoid.
ALot of useful info can be found at
www.zdspb.com