Fulica americana vs water hen

Fulica americana and water hen both are nouns.

Word	Noun	Adjective	Verb	Adverb
Fulica americana	Yes	No	No	No
water hen	Yes	No	No	No

As nouns, Fulica americana and water hen are synonyms defined as:

Other synonyms of Fulica americana include American coot, marsh hen, mud hen.

Fulica americana (noun)	water hen (noun)
a coot found in North America	any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens
	a coot found in North America