iTunes match
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your library of up to 100,000 songs is stored on iCloud, and can be streamed or downloaded to other devices.
you do not get apple radio
songs that you pirated can be turned in for iTunes store copies ( 256 bit rate )
songs that you bought from iTunes earlier can be traded in for iTunes plus files.
whatever music you upgraded is yours to keep forever, even if you cancel
apple music
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see above
you do get apple radio
you can download all the songs you want as long as apple offers them.
whatever music you downloaded is forfeited if you cancel
im not sure about "trading in" on apple music.
you can't sync your iTunes song library to any device with these things turned on
trading in
basically what I'm saying is that if you have a lot of mp3s , iTunes will match these with their higher quality copies.
once the matching process is complete. you can delete all those old songs, and download their copies.
if you have old iTunes songs that are DRM'ed ( that have the 10 device limit ) they can be deleted from your library
and you can download DRM FREE iTunes plus files, which you can keep forever. just don't give them away, because
they all have your email address in them
apple music allows you to download any of apple's "select" music from the store , without having to pay for it. if you have itunes match and you want metallica or iron maiden, you're going to have to buy the cds or buy them from the store.
if you have apple music and you want metallica or iron maiden, you can just downloaded it. but those tracks will no longer be playable if you cancel apple music
apple music does NOT give you access to EVERY SINGLE song. its a "collection" of songs that apple chooses to put on apple music.
once purchased music has no DRM ( iTunes plus ) a computer running iTunes no longer needs to be signed into apple at all, or even authorized to play the song.