Apple Music vs. Spotify: Where does the differences stand?

Since the Apple unveiled Apple Music at WWDC 2015 on 8 June, Spotify's CEO and founder Daniel Ek seemed very worried about the battle between Apple Music and his Spotify. It's very obvious when you tweet ''Oh ok" and delete it after a while. Apple Music came automatically with the iOS 8.4 update. And it seems even a bigger potential threat with the upcoming iOS 9 release.