sirenian vs manatee

sirenian and manatee both are nouns.

Word	Noun	Adjective	Verb	Adverb
sirenian	Yes	No	No	No
manatee	Yes	No	No	No

As nouns, manatee is a hyponym of sirenian; that is, manatee is a word with a more specific, narrower meaning than sirenian:

sirenian: any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs
manatee: sirenian mammal of tropical coastal waters of America; the flat tail is rounded

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

sirenian (noun)	manatee (noun)
any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs	sirenian mammal of tropical coastal waters of America; the flat tail is rounded