imitation vs forgery

imitation and forgery both are nouns.

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

As nouns, forgery is a hyponym of imitation; that is, forgery is a word with a more specific, narrower meaning than imitation:

Other hyponyms of imitation include fake, postiche, sham, counterfeit.

imitation (noun)	forgery (noun)
copying (or trying to copy) the actions of someone else	criminal falsification by making or altering an instrument with intent to defraud
something copied or derived from an original	a copy that is represented as the 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)	forgery (adjective)
not genuine or real; being an imitation of the genuine article