writer vs author

writer and author both are nouns.

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

As nouns, writer and author are synonyms defined as:

writer and author: writes (books or stories or articles or the like) professionally (for pay)

writer (noun)	author (noun)
writes (books or stories or articles or the like) professionally (for pay)	writes (books or stories or articles or the like) professionally (for pay)
a person who is able to write and has written something	someone who originates or causes or initiates something

writer (verb)	author (verb)
	be the author of