What does "Merge" or "Replace" do to your iCloud Music Library?

[venividivigor]

My iPhone is experiencing problems when it comes to saving playlists offline... I get an error "This item cannot be download". I wanna attempt to turn off/on my iCloud Music Library on my phone, but I'm afraid to reset it or cause a mess with duplicates and stuff.

Should I merge or replace?

 

[Julien]

Merge will keep what music is on your iPhone and if not part of AM/iCML will add to or if part of iCML and updated or different info (like a metadata change) will update.

Replace erases all music on your iPhone and uses iCML as it is.