effigy vs scarecrow

effigy and scarecrow both are nouns.

Word	Noun	Adjective	Verb	Adverb
effigy	Yes	No	No	No
scarecrow	Yes	No	No	No

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

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

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

effigy (noun)	scarecrow (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