river horse vs artiodactyl

river horse and artiodactyl both are nouns.

Word	Noun	Adjective	Verb	Adverb
river horse	Yes	No	No	No
artiodactyl	Yes	Yes	No	No

As nouns, artiodactyl is a hypernym of river horse; that is, artiodactyl is a word with a broader meaning than river horse:

river horse: massive thick-skinned herbivorous animal living in or around rivers of tropical Africa
artiodactyl: placental mammal having hooves with an even number of functional toes on each foot

Other hypernyms of river horse include artiodactyl mammal, even-toed ungulate.

river horse (noun)	artiodactyl (noun)
massive thick-skinned herbivorous animal living in or around rivers of tropical Africa	placental mammal having hooves with an even number of functional toes on each foot

river horse (adjective)	artiodactyl (adjective)
	of or relating to or belonging to mammals of the order Artiodactyla