songwriter vs composer

songwriter and composer both are nouns.

Word	Noun	Adjective	Verb	Adverb
songwriter	Yes	No	No	No
composer	Yes	No	No	No

As nouns, composer is a hypernym of songwriter; that is, composer is a word with a broader meaning than songwriter:

songwriter (noun)	composer (noun)
a composer of words or music for popular songs	someone who composes music, usually as a profession