Audio Quality: Apple Music vs. Spotify

With Apple Music and Spotify set on their highest settings, here are my impressions:

1. Spotify sounds negligibly louder (playback - loudness levels set to "normal") than Apple Music (with "sound check" toggled on).
2. It does seem at first that Spotify has more body to the music than Apple Music. Everything just seems to be a "fuller" experience on Spotify.
3. However, upon careful and multiple episodes of listening, it seems that Apple Music has far more breathing room. This enables a more spaced out (differentiated?) separation of instruments. But overall, it still sounds "thinner" than Spotify (ref: last point). This could be due to multiple reasons - good or bad. Arguably, a "thinner" sound profile does help in better breathing of instruments and clearer separation. But this could be perceptively poorer in quality.
4. Here's the funny bit though: in the absence of a professional and unbiased evaluation, it is very difficult to say if the different sound profiles are due to a difference in quality. Sometimes, audio with less details (let's say 128 kbps vs 256 kbps) and poor mastering (bad loudness levels) could sound good upon the first quick listening. But it's only with sustained listening that a more authentic judgement becomes clearer. When it comes to audio, first impressions could be misleading.

If anyone has impressions, they will be useful. As consumers, we should not loose focus on audio quality amidst the streaming wars between all these platforms.

PS: The aforesaid impressions were based on listening to both the platforms on an iPhone. Both apps were updated.