baron vs big businessman

baron and big businessman both are nouns.

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

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

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

baron (noun)	big businessman (noun)
a British peer of the lowest rank	a very wealthy or powerful businessman
a very wealthy or powerful businessman
a nobleman (in various countries) of varying rank