h.264 with mov vs mp4 extension?

I notice that the h.264 iPhone preset in Compressor makes a mp4 file whereas the h.264 for hi-band (web) makes a mov file. Why? To quote a white-paper on the subject from Intelligent Assistance it says "Apple is supporting mp4 because it is fully supported by Quicktime plus it is more widely compatible with non-Apple MPEG-4 players"

I know there are grey areas* here but isn't it limiting to use the mov extension if one want to comply with non-Apple MPEG-4 players?

(* for me it's grey to the extent that h.264 = mpeg-4 yes? and that if I manually change the above mov extension to mp4 it plays locally and in most web test fine)

Thanks for any clarification

Paul