Walker vs author

Walker and author both are nouns.

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

Walker (noun)	author (noun)
United States writer (born in 1944)	writes (books or stories or articles or the like) professionally (for pay)
New Zealand runner who in 1975 became the first person to run a mile in less than 3 minutes and 50 seconds (born in 1952)	someone who originates or causes or initiates something

Walker (verb)	author (verb)
	be the author of