manikin vs dummy

manikin and dummy both are nouns.

Word	Noun	Adjective	Verb	Adverb
manikin	Yes	No	No	No
dummy	Yes	Yes	Yes	No

As nouns, dummy is a hypernym of manikin; that is, dummy is a word with a broader meaning than manikin:

manikin (noun)	dummy (noun)
a life-size dummy used to display clothes	a figure representing the human form
a person who is very small but who is not otherwise deformed or abnormal	a cartridge containing an explosive charge but no bullet
a woman who wears clothes to display fashions	an ignorant or foolish person
	a person who does not talk

manikin (adjective)	dummy (adjective)
	having the appearance of being real but lacking capacity to function

manikin (verb)	dummy (verb)
	make a dummy of