water orchid vs water hyacinth

water orchid and water hyacinth both are nouns.

Word	Noun	Adjective	Verb	Adverb
water orchid	Yes	No	No	No
water hyacinth	Yes	No	No	No

As nouns, water orchid and water hyacinth are synonyms defined as:

water orchid and water hyacinth: a tropical floating aquatic plant having spikes of large blue flowers; troublesome in clogging waterways especially in southern United States

Other synonyms of water orchid include Eichhornia crassipes, Eichhornia spesiosa.

water orchid (noun)	water hyacinth (noun)
a tropical floating aquatic plant having spikes of large blue flowers; troublesome in clogging waterways especially in southern United States	a tropical floating aquatic plant having spikes of large blue flowers; troublesome in clogging waterways especially in southern United States