water pimpernel vs hydrophyte

water pimpernel and hydrophyte both are nouns.

Word	Noun	Adjective	Verb	Adverb
water pimpernel	Yes	No	No	No
hydrophyte	Yes	No	No	No

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

water pimpernel: a white-flowered aquatic plant of the genus Samolus
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 pimpernel include aquatic plant, hydrophytic plant, water plant.

water pimpernel (noun)	hydrophyte (noun)
a white-flowered aquatic plant of the genus Samolus	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