waterweed vs hydrophytic plant

waterweed and hydrophytic plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
waterweed	Yes	No	No	No
hydrophytic plant	Yes	No	No	No

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

waterweed: a weedy aquatic plant of genus Elodea
hydrophytic plant: 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 waterweed include aquatic plant, hydrophyte, water plant.

waterweed (noun)	hydrophytic plant (noun)
a weedy aquatic plant of genus Elodea	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