mud hen vs Fulica americana

mud hen and Fulica americana both are nouns.

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

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

Other synonyms of mud hen include American coot, marsh hen, water hen.

mud hen (noun)	Fulica americana (noun)
a coot found in North America	a coot found in North America