look-alike vs actor

look-alike and actor both are nouns.

Word	Noun	Adjective	Verb	Adverb
look-alike	Yes	Yes	No	No
actor	Yes	No	No	No

As nouns, actor is a hypernym of look-alike; that is, actor is a word with a broader meaning than look-alike:

look-alike: someone who closely resembles a famous person (especially an actor)
actor: a person who acts and gets things done

Other hypernyms of look-alike include doer, worker.

look-alike (noun)	actor (noun)
someone who closely resembles a famous person (especially an actor)	a theatrical performer
	a person who acts and gets things done

look-alike (adjective)	actor (adjective)
resembling closely