Author or artist?

Why are the people who make books called authors and the people who make music called artists? In my eyes both are a form of art. Music paints a pic in your mind when you listen close enough. Books paint an even more detailed pick when you read it. What's the huge difference? Most songs have a story to them. Many people can make connections to books. It's also easy to connect to music.
Should an author be considered an artist? Really besides the difference of singing ot writing your 'story'.
Really almost all the songs I know of have SOME kind of point or story line.
So author or artist?
What do you think?