Singer vs author

Singer and author both are nouns.

Word	Noun	Adjective	Verb	Adverb
Singer	Yes	No	No	No
author	Yes	No	Yes	No

Singer (noun)	author (noun)
United States writer (born in Poland) of Yiddish stories and novels (1904-1991)	writes (books or stories or articles or the like) professionally (for pay)
United States inventor of an improved chain-stitch sewing machine (1811-1875)	someone who originates or causes or initiates something

Singer (verb)	author (verb)
	be the author of