American frogbit vs water plant

American frogbit and water plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
American frogbit	Yes	No	No	No
water plant	Yes	No	No	No

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

American frogbit: American plant with roundish heart-shaped or kidney-shaped leaves; usually rooted in muddy bottoms of ponds and ditches
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 American frogbit include aquatic plant, hydrophyte, hydrophytic plant.

American frogbit (noun)	water plant (noun)
American plant with roundish heart-shaped or kidney-shaped leaves; usually rooted in muddy bottoms of ponds and ditches	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