If you only sing and don't know anything about music or do not play any kind of instrument, you're a vocalist.
Just wondering.. Those that sing in the shower.. Are they considered vocalists also??
Imo humbly so, a trained vocalists (a singer in the case deb might be refering to) requires in depth knowledge of music, articulation and timing and extensive vocal training such to refining how to master ones instrument. And such would have rightly obtain their title as a musician.