Essentially Facebook caters to a smaller niche population; the percentage of people using Facebook doesn't compared to Myspace. You don't need an account to access an artist's Myspace site and besides, Myspace is more functional, intuitive, not to mention, customizable. Facebook is a great tool for outreaching fans and I think the new music section is great, but it is more of a social networking for friends/students/club than anything else.