illegal vs criminal

illegal is not a noun while criminal is a noun.

Word	Noun	Adjective	Verb	Adverb
illegal	No	Yes	No	No
criminal	Yes	Yes	No	No

illegal (noun)	criminal (noun)
	someone who has committed a crime or has been legally convicted of a crime

illegal (adjective)	criminal (adjective)
prohibited by law or by official or accepted rules	guilty of crime or serious offense
	involving or being or having the nature of a crime
	bringing or deserving severe rebuke or censure