ground sloth vs megathere

ground sloth and megathere both are nouns.

Word	Noun	Adjective	Verb	Adverb
ground sloth	Yes	No	No	No
megathere	Yes	No	No	No

As nouns, ground sloth and megathere are synonyms defined as:

ground sloth and megathere: gigantic extinct terrestrial sloth-like mammal of the Pliocene and Pleistocene in America

ground sloth (noun)	megathere (noun)
gigantic extinct terrestrial sloth-like mammal of the Pliocene and Pleistocene in America	gigantic extinct terrestrial sloth-like mammal of the Pliocene and Pleistocene in America