"Consumer" stand-alone audio CD recorders require special blanks. See
section (5-12) for details. There is no difference in quality or composition between "data" blanks and "music" blanks, except for a flag that indicates which one it is. It's likely that "music" blanks are optimized for recording at 1x, since anything you record "live" is by definition recorded at 1x (though some dual-drive systems allow track copying at higher speeds).
You don't have to use "music" blanks to record music on a computer or on a "professional" stand-alone audio CD recorder. Nothing will prevent you from doing so, but there's no advantage to it.
The "music" blanks are more expensive than the "data" blanks because a portion of the price goes to the music industry. The specifics vary from country to country. In the USA, the money goes to the RIAA, which distributes it to artists who have navigated through a complicated application process.