I think it is interesting to compare Wentworth to St George's Hill, given that they were built by the same developer (Tarrant) and same architect (Colt obviously, although John Morrison did a lot of the work at Wentworth).
The most obvious difference is in the masterplan/routing. Compare the West to the main course at SGH and it is night and day -- Wentworth is, apart from the small loop at the far end of the course, wholly linear, with houses on both sides of the holes, and a much more 'parkland' feel, even before the recent work. It's no coincidence that the nicest part of the West is the run from 7-13 (apart from the horrors that have been inflicted on number eight), where you are not surrounded by houses and there's still a heath feel. The houses feel closer to the golf at Wentworth than at SGH, where you know you are playing through a housing estate, but it only occasionally impinges on the golf.
It is also important to note that Wentworth had 36 holes from day one, whereas at SGH the second course was an afterthought.