big businessman vs tycoon

big businessman and tycoon both are nouns.

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

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

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

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