high-up vs high muckamuck

high-up and high muckamuck both are nouns.

Word	Noun	Adjective	Verb	Adverb
high-up	Yes	No	No	No
high muckamuck	Yes	No	No	No

As nouns, high-up and high muckamuck are synonyms defined as:

high-up and high muckamuck: an important or influential (and often overbearing) person

Other synonyms of high-up include dignitary, panjandrum, very important person, VIP.

high-up (noun)	high muckamuck (noun)
an important or influential (and often overbearing) person	an important or influential (and often overbearing) person