writing credits

[ross.reyes]

> I just looked at the number of times a Bouchard was
>credited to a song vs. no Bouchard being credited -- if I counted right,
>44 out of 72 songs had a Bouchard song-writing credit from the first
>album to FOUO (61%).

Someone please answer:

I thought that a writing credit was given for the lyrical content
of the song, not necessarily for the music.  Is there a distinction?

I had thought that the writer brings in the lyrical stuff, maybe
some loose ideas on the music, and the rest of the band chimes
in to flesh out a complete tune.  Is that way off?

RR