coho salmon vs Oncorhynchus

coho salmon and Oncorhynchus both are nouns.

Word	Noun	Adjective	Verb	Adverb
coho salmon	Yes	No	No	No
Oncorhynchus	Yes	No	No	No

coho salmon (noun)	Oncorhynchus (noun)
small salmon of northern Pacific coasts and the Great Lakes	Pacific salmon including sockeye salmon, chinook salmon, chum salmon, coho salmon
fatty pinkish flesh of small salmon caught in the Pacific and Great Lakes