plantigrade mammal vs eutherian

plantigrade mammal and eutherian both are nouns.

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

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

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

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

plantigrade mammal (noun)	eutherian (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 mammal (adjective)	eutherian (adjective)
	of or relating to or belonging to the subclass Eutheria