sea cow vs Dugong dugon

sea cow and Dugong dugon both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea cow	Yes	No	No	No
Dugong dugon	Yes	No	No	No

As nouns, Dugong dugon is a hyponym of sea cow; that is, Dugong dugon is a word with a more specific, narrower meaning than sea cow:

sea cow: any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs
Dugong dugon: sirenian tusked mammal found from eastern Africa to Australia; the flat tail is bilobate

Other hyponyms of sea cow include manatee, Trichechus manatus, dugong, Hydrodamalis gigas, Steller's sea cow.

sea cow (noun)	Dugong dugon (noun)
any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs	sirenian tusked mammal found from eastern Africa to Australia; the flat tail is bilobate