Difference between Artisan Bespoke 002 & 004 mattresses

I called yourself for advice and was told to try Visprung mattresses which I did only to find yours is a different product. Presently sleeping on medium mattress on slated frame which was fine until a year ago when I found every morning when I got up my back hurt. On rotating mattress the pain diminished so realise a new mattress is needed. I'm 9 stone and 5'6, husband 14.5 stone and 6'2. Side sleeper with niggling hip. Friend recommended bespoke medium 02/04 but not sure what's best for me. Can you help?