I had a pair of 805 sig's and I can tell you this the difference for one is in the up graded cross over that is used in the Signature line over the Nautalus line. In the 805 Sigs you are also getting the same speakers that are used in the 802's. The Sig's offer a better soundstage and bass response over the 805N. There are 2 finishes available, Red Birds Eye & also Gray Tigers Eye, both are awesome to look at and both are finished with 40 coats of clear coat. A dealer telling you there is no difference in the 2 other then the finish, really should not be a dealer to start with.
Dave
Dave