Artisan Tailored Pocket 2000 and Artisan Naturals comparison

Hi JohnRyan, This may already have been asked before but with the absolute wealth of information on the site I haven't been alble to find it. Can you tell me what, in simple terms, the actual differences are between the Artisan Tailored Pocket 2000 and the Artisan Naturals that warrent the extra £110 please. Also, as like most couples we are 2 differnt sizes I come in at 6ft and 17st and my wife 5ft 2ins and 12 stone. I suffer from bulging discs and my wife various joint complaints In your opinion would a medium or firm mattress be the better option?

Many thanks for an extremely formative site. Tony .