I used to have both - the top one is a typical Putnam edition - a well researched history type-by-type of RAF designs with lots of text, some photographs and some tiny 3-view drawings, primarily aimed at the aviation historian rather than the modeller.
The lower one is a typical Crowood coffee-table volume, with lots of pictures but rather more sketchy text, probably of more interest to the casual reader rather than the specialist.
The Datafiles, Air-Britain SE5 File and some individual monographs are better for the modeller as opposed to the book collector in my opinion.
Sandy.