aquatic vs plant life

aquatic and plant life both are nouns.

Word	Noun	Adjective	Verb	Adverb
aquatic	Yes	Yes	No	No
plant life	Yes	No	No	No

As nouns, plant life is a hypernym of aquatic; that is, plant life is a word with a broader meaning than aquatic:

Other hypernyms of aquatic include flora, plant.

aquatic (noun)	plant life (noun)
a plant that lives in or on water	(botany) a living organism lacking the power of locomotion

aquatic (adjective)	plant life (adjective)
operating or living or growing in water
relating to or consisting of or being in water