chum vs Oncorhynchus keta

chum and Oncorhynchus keta both are nouns.

Word	Noun	Adjective	Verb	Adverb
chum	Yes	No	No	No
Oncorhynchus keta	Yes	No	No	No

As nouns, chum and Oncorhynchus keta are synonyms defined as:

chum and Oncorhynchus keta: a large Pacific salmon with small spots on its back; an important food fish

Other synonyms of chum include chum salmon.

chum (noun)	Oncorhynchus keta (noun)
a large Pacific salmon with small spots on its back; an important food fish	a large Pacific salmon with small spots on its back; an important food fish
bait consisting of chopped fish and fish oils that are dumped overboard to attract fish
a close friend who accompanies his buddies in their activities