Different masters can of course be more or less…different, but if you look at the graphs in my post #66, I’d say it’s quite possible to hear a difference on these. Either on tonal balance or level.That the masters are different can be objectively proven, so far I've seen no evidence that the differences are audible. If the differences are just encoding technologies it makes me skeptical. If the differences are also due to a re-mix of the multi-track masters, maybe.
As for your last question... we're going to help Apple and Amazon select masters for 60 million or more songs?