water trumpet vs aquatic plant

water trumpet and aquatic plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
water trumpet	Yes	No	No	No
aquatic plant	Yes	No	No	No

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

water trumpet: any plant of the genus Cryptocoryne; evergreen perennials growing in fresh or brackish water; tropical Asia
aquatic 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 water trumpet include hydrophyte, hydrophytic plant, water plant.

water trumpet (noun)	aquatic plant (noun)
any plant of the genus Cryptocoryne; evergreen perennials growing in fresh or brackish water; tropical Asia	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