duckweed vs hydrophytic plant

duckweed and hydrophytic plant both are nouns.

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

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

duckweed: any small or minute aquatic plant of the family Lemnaceae that float on or near the surface of shallow ponds
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 duckweed include aquatic plant, hydrophyte, water plant.

duckweed (noun)	hydrophytic plant (noun)
any small or minute aquatic plant of the family Lemnaceae that float on or near the surface of shallow ponds	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