imitation vs artificial

imitation is a noun but artificial is not a noun.

Word	Noun	Adjective	Verb	Adverb
imitation	Yes	Yes	No	No
artificial	No	Yes	No	No

imitation (noun)	artificial (noun)
copying (or trying to copy) the actions of someone else
something copied or derived from an original
the doctrine that representations of nature or human behavior should be accurate imitations
a representation of a person that is exaggerated for comic effect

imitation (adjective)	artificial (adjective)
not genuine or real; being an imitation of the genuine article	contrived by art rather than nature
	artificially formal
	not arising from natural growth or characterized by vital processes