I don’t remember when i started using Spotify but some time ago i decided to try Google Music. I’ve used it for one month. It is my short comparison - just advantages because both services are very similar.
Google Music
- music divided into types
- it is possible to upload 20000 of own music files
Spotify
- it has more music which i listen to, i couldn’t find all music from Spotify
- more options
- family sharing
- desktop application
- integration (out of the box) with last.fm
- using Google Music i had to wait 1-2 second before music was started (buffer), Spotify plays music immediately
- i can see music listened by my friends
- i can share playlist with my friends
- Spotify more often suggests new music
- in my opinion - Spotify has better algorithm for showing similar music
Spotify wins.