effigy vs bird-scarer

effigy and bird-scarer both are nouns.

Word	Noun	Adjective	Verb	Adverb
effigy	Yes	No	No	No
bird-scarer	Yes	No	No	No

As nouns, bird-scarer is a hyponym of effigy; that is, bird-scarer is a word with a more specific, narrower meaning than effigy:

effigy: a representation of a person (especially in the form of sculpture)
bird-scarer: an effigy in the shape of a man to frighten birds away from seeds

Other hyponyms of effigy include Guy, god, graven image, idol, scarecrow, scarer, straw man, strawman, wax figure, waxwork, close-up.

effigy (noun)	bird-scarer (noun)
a representation of a person (especially in the form of sculpture)	an effigy in the shape of a man to frighten birds away from seeds