acumen vs perspicaciousness

acumen and perspicaciousness both are nouns.

Word	Noun	Adjective	Verb	Adverb
acumen	Yes	No	No	No
perspicaciousness	Yes	No	No	No

As nouns, perspicaciousness is a hypernym of acumen; that is, perspicaciousness is a word with a broader meaning than acumen:

acumen: shrewdness shown by keen insight
perspicaciousness: intelligence manifested by being astute (as in business dealings)

Other hypernyms of acumen include astuteness, perspicacity, shrewdness.

acumen (noun)	perspicaciousness (noun)
shrewdness shown by keen insight	intelligence manifested by being astute (as in business dealings)
a tapering point