B&W 804nautilus vs. 804s

Can anyone tell me the major differences between the 804nautilus and the 804s? I'm kind of a dummy when it comes to this, and my research hasn't given much info. Differences in mnfr.date, sound quality, etc. I'm putting together a system, and have a chance at buying either one used in excellent shape. HELP!?!
The signature series have the same tweeters like the tweeters on 802, 801, & 800.
It appears you haven't recieved very good responses yet. The original nautilus series was made availabe in 1997. It was a drastic change over the previous matrix series. It served B&W well for many years. The next iteration (late 2004) used an "S" in the model name. The "S" had nothing to do with the "Signature" line. The signature line only offered the 800, 805, and the center. The "S" came after the signature and included the entire 800 series in the line.

The tweeter from the signature line was shared in the newer "S" line, except for the 803D, 802D, 801D, and 800D. Those carried the diamond tweeter represented by the D in the name. I've owned the Nautilus 805, Signature 805, and the 805S. Based on my experience, the signature 805 was a significant improvement over the standard N805. The 805S was much closer to the signature sound (some say even better).

I also auditioned the N804 on many occassions and owned the 804S for a short time. In my opinion, the "S" line is more balanced, offers better bass, is smoother in the upper end and is just more enjoyable to listen to. There is a price difference on the used market between the N804 and the 804S, but given the choice, it'd be a no brainer for me. I'd take the 804S.

Hope this helps.
When you say 804's do you mean matrix 804. I have the matrix 802 s3 and was going to upgrade to the Nauty 802 but opted for a Xover upgrade. Amazing soundstage and imaging now, coupled with a crystal clear shimmering treble. Very happy, so you decide. also depends on the amp and preamp. I like solid amp and tubed pre. solid iron fisted bass with bloom in the mids and treble.