contributor vs author

contributor and author both are nouns.

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

As nouns, author is a hypernym of contributor; that is, author is a word with a broader meaning than contributor:

contributor: a writer whose work is published in a newspaper or magazine or as part of a book
author: writes (books or stories or articles or the like) professionally (for pay)

Other hypernyms of contributor include writer.

contributor (noun)	author (noun)
someone who contributes (or promises to contribute) a sum of money	writes (books or stories or articles or the like) professionally (for pay)
a writer whose work is published in a newspaper or magazine or as part of a book	someone who originates or causes or initiates something

contributor (verb)	author (verb)
	be the author of