big enchilada vs big cheese

big enchilada and big cheese both are nouns.

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

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

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

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