companion vs accompany

companion is a noun but accompany is not a noun.

Word	Noun	Adjective	Verb	Adverb
companion	Yes	No	Yes	No
accompany	No	No	Yes	No

As verbs, companion and accompany are synonyms defined as:

Other synonyms of companion include company, keep company.

companion (noun)	accompany (noun)
a friend who is frequently in the company of another
one paid to accompany or assist or live with another
a traveler who accompanies you

companion (verb)	accompany (verb)
be a companion to somebody	perform an accompaniment to
	go or travel along with
	be present or associated with an event or entity
	be a companion to somebody