They are not always the same but there is more overlap than you would think. One place that I know is being hit hard is Nashville (no comment on what this implies about the state of US country music). There are a lot of local musicians with their own (small) bands whose primary income came from (relatively low quality, compared to their own music) song-writing, playing back-up instrumentals/vocals for studios, stuff like that. This income stream is shrinking rapidly.