water star grass vs hydrophyte

water star grass and hydrophyte both are nouns.

Word	Noun	Adjective	Verb	Adverb
water star grass	Yes	No	No	No
hydrophyte	Yes	No	No	No

As nouns, hydrophyte is a hypernym of water star grass; that is, hydrophyte is a word with a broader meaning than water star grass:

water star grass: grassy-leaved North American aquatic plant with yellow star-shaped blossoms
hydrophyte: a plant that grows partly or wholly in water whether rooted in the mud, as a lotus, or floating without anchorage, as the water hyacinth

Other hypernyms of water star grass include aquatic plant, hydrophytic plant, water plant.

water star grass (noun)	hydrophyte (noun)
grassy-leaved North American aquatic plant with yellow star-shaped blossoms	a plant that grows partly or wholly in water whether rooted in the mud, as a lotus, or floating without anchorage, as the water hyacinth