Hey Hans congratulations on the Oscar... 
If you listen to John William's 1st Violin Concerto and then compare it to his film work, you might get a sense of why he himself considers his film work distinct and a different musical aesthetic and technique to his concert work. Comparison of the two disciplines at work (yes, they are different disciplines in crucial areas), from a compositional and sounding point of view should go all the way to answering your question.
I've said this before in conversation with member Fabulin (who will chime in no doubt and make me waver in my opinion on the OP dilemna), that JW is quite unique in that his cue writing (as opposed to his excellent theme writing), is good enough to pass off as a more serious stand alone offering in the concert hall.
But it is rather telling that when he sits down and purposely writes for the concert hall, the language in particular is much more personal and one hears that his mindset and expressive reach is different and more personal. In other words just what you expect from absolute music, that of music from a deeper place within who's genesis is not instigated by what is fundamentally utility.
If you listen to John William's 1st Violin Concerto and then compare it to his film work, you might get a sense of why he himself considers his film work distinct and a different musical aesthetic and technique to his concert work. Comparison of the two disciplines at work (yes, they are different disciplines in crucial areas), from a compositional and sounding point of view should go all the way to answering your question.
I've said this before in conversation with member Fabulin (who will chime in no doubt and make me waver in my opinion on the OP dilemna), that JW is quite unique in that his cue writing (as opposed to his excellent theme writing), is good enough to pass off as a more serious stand alone offering in the concert hall.
But it is rather telling that when he sits down and purposely writes for the concert hall, the language in particular is much more personal and one hears that his mindset and expressive reach is different and more personal. In other words just what you expect from absolute music, that of music from a deeper place within who's genesis is not instigated by what is fundamentally utility.