B&W 805 models...

I guess the one on the B&W website is the newest model that is called '805S'.

First of all, what could be the S stands for? Standard? Signature?

Is '805S' = 'Signature 805'?

What are the different models such as matrix 805, signature 805, nautilus 805, 805S etc..., and which is oldest, older, newer, newest, etc...