Sorry for the late reply.
Some of them I do believe are different recordings (possible remasters).Some are identical recording versions.
I can play the same track on Spotify or on cd or Amazon. And they are different. I do think Spotify is more heavily compressed, which for some songs is nice. But for others, not so nice.
Though Playing a cd vs Amazon is only a slight difference. All the comparison back and fourth over the last week and a half has given me a headache. (LOL) My conclusion, none of them are necessarily good or bad, better or worse. Just kind of depends on what flavor one may or may not prefer.
Yep, I get what your saying. Kind of like comparing a album recorded in a studio vs on a stage.
Or like having the singer or band almost in your face vs stepping back 10' or so.
On some music I prefer the up front in your face, others I do enjoy the music being set back somewhat.
The one thing I will credit to the sound coming from amazon hd is. Speakers do seem to disappear much easier. So I could see why that could be a good thing.
But you are right there are things that are different. And I couldn't swear to exactly why that is.