This is a pure opinion of mine and compares the two streaming services on my needs only. I will not compare all the features but just the differences i discovered. If you do not know Spotify or Rdio I recommand to take a look at them. Both provide a very good service.
I have to give both of them credits for the huge device support they have. OSX, Windows, Web, iOS, Android, Windows Phone and Blackberry its all there to download. I have not tried all of them, but i suspect they do their job on every platform.
When you use the Spotify and Rdio app, the first thing to notice is that Spotify is just so much faster. Rdio is sometimes so slow that I wonder if Spotify's Peer-to-Peer technology alone can make that much a difference? Anyway this is not a dealbreaker but totally annoying.
Mobile apps (iOS)
I have only used the iOS apps on an iPhone so far. Either of them gives you the same functionality as their website. Not much difference here.
In case of the design there can only be one winner: Rdio. It is not that Spotify's design is ugly but the guys from Rdio did just a better job.
Features and Functionality
Rdio has one awesome feature. Every app you have running with the same account is automatically a remote control for the app that currently plays music. So your smartphone can control the web-player and vice versa.
Next up I have a few things that Rdio is really missing and made me switch to Spotify again.
- mobile apps dont remember shuffle
- you can not search you own playlist for a song
- you can not sort your playlist by anything
- Rdio can not play you own music unlike Spotify. So no AC/DC for example.
- Rdio does not let you see the upcoming songs.
One awesome feature and a better design does not compensate the missing functionality. And most of it are just very basic things I expect to see on every music player. For me Spotify is the better solution and I will stick to it for now.