polygamy vs polyandry

polygamy and polyandry both are nouns.

Word	Noun	Adjective	Verb	Adverb
polygamy	Yes	No	No	No
polyandry	Yes	No	No	No

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

polygamy: the condition or practice of having more than one spouse at a time
polyandry: the state of having more than one husband at a time

Other hyponyms of polygamy include polygyny.

polygamy (noun)	polyandry (noun)
the condition or practice of having more than one spouse at a time	the state of having more than one husband at a time