What is a Stream?
Stream refers to a song that's played from a server rather than the source file downloaded to your local machine (which is a download). With Yahoo! Music Unlimited, you select in the Preferences section of the Yahoo! Music Jukebox whether you prefer subscription tracks to stream or be downloaded to your local computer.
Streaming music can only be enjoyed when you are connected to the Internet. Music you have selected to download, however, can be played whether you are online or offline.
Yahoo! LAUNCHcast Plus Radio, which comes with your Yahoo! Music Unlimited subscription, is a streaming audio service.