big cheese vs big enchilada

big cheese and big enchilada both are nouns.

Word	Noun	Adjective	Verb	Adverb
big cheese	Yes	No	No	No
big enchilada	Yes	No	No	No

As nouns, big cheese and big enchilada are synonyms defined as:

Other synonyms of big cheese include big deal, big fish, big gun, big shot, big wheel, head honcho.

big cheese (noun)	big enchilada (noun)
an important influential person	an important influential person