Opuntia tuna vs tuna

Opuntia tuna and tuna both are nouns.

Word	Noun	Adjective	Verb	Adverb
Opuntia tuna	Yes	No	No	No
tuna	Yes	No	No	No

As nouns, Opuntia tuna and tuna are synonyms defined as:

Opuntia tuna (noun)	tuna (noun)
tropical American prickly pear of Jamaica	any very large marine food and game fish of the genus Thunnus; related to mackerel; chiefly of warm waters
	New Zealand eel
	important warm-water fatty fish of the genus Thunnus of the family Scombridae; usually served as steaks
	tropical American prickly pear of Jamaica