mogul vs big businessman

mogul and big businessman both are nouns.

Word	Noun	Adjective	Verb	Adverb
mogul	Yes	No	No	No
big businessman	Yes	No	No	No

As nouns, mogul and big businessman are synonyms defined as:

Other synonyms of mogul include baron, business leader, king, magnate, power, top executive, tycoon.

mogul (noun)	big businessman (noun)
a very wealthy or powerful businessman	a very wealthy or powerful businessman
a bump on a ski slope