big wheel vs big shot

big wheel and big shot both are nouns.

Word	Noun	Adjective	Verb	Adverb
big wheel	Yes	No	No	No
big shot	Yes	No	No	No

As nouns, big wheel and big shot are synonyms defined as:

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

big wheel (noun)	big shot (noun)
an important influential person	an important influential person