Google has just launched a free version of the Google Play Music streaming service, placing it in direct competition with another free music streaming service, Pandora.

Google Play Music started out with a subscription-based model for its services, charging users a monthly fee of $9.99 to allow them to stream over 30 million songs, store as many as 50,000 purchased tracks and create customized playlists. The service competed directly with Spotify, an upcoming rival once Apple Music launches.

The free, ad-supported version of Google Play Music that was launched, however, will instead be going up against Pandora. Being the free version of the service, there will be some capabilities that will be limited.

For example, users are not allowed to choose the songs that they listen to. Instead, users choose from different digital radio stations that are organized, depending on mood, genre, activity or decade. Users can also search for a specific artist, song or album, with the service returning a collection of music related to the search query. This system is similar to what Pandora utilizes in its free music streaming service.

The top 10 activities that are most popular on Google Play Music, each offering several stations within them, are as follows:

- Brand New Music

- Driving

- Working Out

- Boosting Your Energy

- Having Friends Over

- Having Fun at Work

- Entering Beast Mode

- Waking Up Happy

- Unwinding

- Bedtime

Google Play Music has better targeting capabilities than its competitors, which means that it can use its music inventory to serve users with advertisements that are better formatted or superior compared with what Pandora provides to its users.

So far, comparisons between the two free music streaming services do not indicate any major differences in the features that they offer to users. Google Play Music's advantage over Pandora, however, is that Google Play Music has the entire Google and Android ecosystem supporting it, which could attract more users that are familiar with Google's other apps and services.

Google Play Music is now available on the Web, and the apps of the service for Android and iOS will be released within the week. The service will first launch in the United States.