featherfoil vs water plant

featherfoil and water plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
featherfoil	Yes	No	No	No
water plant	Yes	No	No	No

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

featherfoil: a plant of the genus Hottonia
water 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 featherfoil include aquatic plant, hydrophyte, hydrophytic plant.

featherfoil (noun)	water plant (noun)
a plant of the genus Hottonia	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