Bit of a guess this but I think that the 748R came with slightly more BHP (presumably from a different engine management system), carbon fibre airbox, ohlins suspension, monopost, road and race cans, race chip, rear stand in colour of frame, bike cover, slipper clutch.
There might be some other things I've forgotten, oh yes, they cost more and need the belts changing annually rather than bi-annually on the S
Apologies if any of this is wrong
(PS. I also think that the paint might be different - I have been told there is a standard red and an anniversary red (?) and although they don't look different, it becomes very obvious when you use the wrong colour touch-up!)