magnate vs big businessman

magnate and big businessman both are nouns.

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

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

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

magnate (noun)	big businessman (noun)
a very wealthy or powerful businessman	a very wealthy or powerful businessman