author vs compose

author is a noun but compose is not a noun.

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

As verbs, compose is a hypernym of author; that is, compose is a word with a broader meaning than author:

Other hypernyms of author include indite, pen, write.

author (noun)	compose (noun)
writes (books or stories or articles or the like) professionally (for pay)
someone who originates or causes or initiates something

author (verb)	compose (verb)
be the author of	make up plans or basic details for
	produce a literary work
	write music
	put together out of existing material
	calm (someone, especially oneself); make quiet
	form the substance of