muscovy duck vs musk duck

muscovy duck and musk duck both are nouns.

Word	Noun	Adjective	Verb	Adverb
muscovy duck	Yes	No	No	No
musk duck	Yes	No	No	No

As nouns, muscovy duck and musk duck are synonyms defined as:

muscovy duck and musk duck: large crested wild duck of Central America and South America; widely domesticated

Other synonyms of muscovy duck include Cairina moschata.

muscovy duck (noun)	musk duck (noun)
large crested wild duck of Central America and South America; widely domesticated	large crested wild duck of Central America and South America; widely domesticated