Apple Music (The app) replaced iTunes (The app), and Apple Music (the service) contains a modified iTunes Match service (which used to only be a separate iTunes

Apple Music (The app) replaced iTunes (The app), and Apple Music (the service) contains a modified iTunes Match service (which used to only be a separate iTunes service) which is still available (the iTunes Match service). The service (iTunes Match) was optional where the Apple Music (the service) method is not optional when using a synced library since part of syncing is matching what is already there. I think that might be what the comment was hinting at. You can use Apple Music (the app) with Apple Music (the service) and disable library syncing, but enable iTunes Match. But at that point, you might as well use Apple Music (the service). Selecting AAC does work in both cases if it's about DRM.