Eutheria vs subclass Eutheria

Eutheria and subclass Eutheria both are nouns.

Word	Noun	Adjective	Verb	Adverb
Eutheria	Yes	No	No	No
subclass Eutheria	Yes	No	No	No

As nouns, Eutheria and subclass Eutheria are synonyms defined as:

Eutheria and subclass Eutheria: all mammals except monotremes and marsupials

Eutheria (noun)	subclass Eutheria (noun)
all mammals except monotremes and marsupials	all mammals except monotremes and marsupials