effigy vs straw man

effigy and straw man both are nouns.

Word	Noun	Adjective	Verb	Adverb
effigy	Yes	No	No	No
straw man	Yes	No	No	No

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

effigy: a representation of a person (especially in the form of sculpture)
straw man: 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, scarecrow, scarer, strawman, wax figure, waxwork, close-up.

effigy (noun)	straw man (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
	a weak or sham argument set up to be easily refuted
	a person used as a cover for some questionable activity