OneDrive
• Add your MP3s to OneDrive and play them wherever you go
• Download playlists albums and songs from OneDrive to enjoy your favorites even when you're off the grid
• See at a glance what's available where (online offline both)

Music Pass
• Discover new songs albums and artists right from your phone
• Play ad-free music from one of the biggest music catalogs on the planet
• Add songs albums and playlists to your Groove music collection and access them from your phone Xbox PC tablet and the web
• Listen to radio stations based on your favorite artists

Groove Support
https://support.microsoft.com/en-us/kb/3079301