I don't use Apple music myself, but I've heard that it doesn't actually use your songs but uses song name matching which sometimes gives you censored versions of explicit songs. Is this true?
I remember when I used Google Play Music and it kept the AOL sound in "my" copy of a certain Tatu song, so that was definitely streaming the uploaded song.
Well, I'm pretty sure GPM did some level of acoustic matching nonsense to optimise storage or bandwidth, because it changed a bunch of songs that I'd uploaded into a different language version of song.
It does that if it can match them, and uploads them if it can't. Downloads on other devices might be 256 kbps AAC either way, so not a backup service.
You cannot officially force an upload, but I would expect there to be some kind of hack for it. If I remember correctly, calling the album "Red Album (sorejan's Version)" actually does the trick.
I remember when I used Google Play Music and it kept the AOL sound in "my" copy of a certain Tatu song, so that was definitely streaming the uploaded song.