Fulica americana vs marsh hen

Fulica americana and marsh hen both are nouns.

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

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

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

Fulica americana (noun)	marsh 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