This is the short fall of the 'net, miscommunication at times; I am not sure what I stated that has you believing that I am confusing the 805 speakers.
Let's get the names straight:
N805 - The origianl Nautilus 805
N805S - The new Nautilus 805 (The new Nautilus line appears that have a suffux of D or S after the model of every speaker, D=Diamond and S=Serialze (?) -- I think that is what I read S was.
S805 - Signature 805, this is not part of the Nautilus line but rather the Prestige line.
As for differences, I can list some between the N805 and S805.
This is taken from What HiFi:
"...But the changes are more than skin-deep: the speakers use an improved tweeter, with a raised top-end cut-off point of 50kHz. Distortion at these high frequencies has been minimised by silver-plating the magnet centre pole."
"The mid/bass unit has also been adjusted to give a faster and tighter response, principally by the adoption of a magnet some 40% bigger than that in the standard N805. An aluminium centre 'bullet' is fitted instead of the standard speaker's plastic piece, thus cleaning up the upper midrange, and the crossover has been extensively upgraded."
I can also note, the obvious beautiful finish, different binding posts and a re-tuning of the Flowport. I will not claim all the above is a complete list, but some I know.
As for the extent of the changes on the new N805S speakers, they were just announced, we don't fully know yet; it appears to be cabinet and some crossover changes for sure, other than that, time will reveal it.