plantigrade vs eutherian mammal

plantigrade and eutherian mammal both are nouns.

Word	Noun	Adjective	Verb	Adverb
plantigrade	Yes	Yes	No	No
eutherian mammal	Yes	No	No	No

As nouns, eutherian mammal is a hypernym of plantigrade; that is, eutherian mammal is a word with a broader meaning than plantigrade:

plantigrade: an animal that walks with the entire sole of the foot touching the ground as e.g. bears and human beings
eutherian mammal: mammals having a placenta; all mammals except monotremes and marsupials

Other hypernyms of plantigrade include eutherian, placental, placental mammal.

plantigrade (noun)	eutherian mammal (noun)
an animal that walks with the entire sole of the foot touching the ground as e.g. bears and human beings	mammals having a placenta; all mammals except monotremes and marsupials

plantigrade (adjective)	eutherian mammal (adjective)
(of mammals) walking on the whole sole of the foot (as rabbits, raccoons, bears, and humans do)