ruddy duck vs Oxyura jamaicensis

ruddy duck and Oxyura jamaicensis both are nouns.

Word	Noun	Adjective	Verb	Adverb
ruddy duck	Yes	No	No	No
Oxyura jamaicensis	Yes	No	No	No

As nouns, ruddy duck and Oxyura jamaicensis are synonyms defined as:

ruddy duck and Oxyura jamaicensis: reddish-brown stiff-tailed duck of North America and northern South America

ruddy duck (noun)	Oxyura jamaicensis (noun)
reddish-brown stiff-tailed duck of North America and northern South America	reddish-brown stiff-tailed duck of North America and northern South America