Spanish mackerel vs Spanish mackerel

Spanish mackerel and Spanish mackerel both are nouns.

Word	Noun	Adjective	Verb	Adverb
Spanish mackerel	Yes	No	No	No
Spanish mackerel	Yes	No	No	No

Spanish mackerel (noun)	Spanish mackerel (noun)
any of several large marine food fishes of the genus Scomberomorus	any of several large marine food fishes of the genus Scomberomorus
medium-sized mackerel of temperate Atlantic and Gulf of Mexico	medium-sized mackerel of temperate Atlantic and Gulf of Mexico
a California food fish	a California food fish
flesh of commercially important fishes especially of the Atlantic coastal waters of America	flesh of commercially important fishes especially of the Atlantic coastal waters of America