business activity vs enterprise

business activity and enterprise both are nouns.

Word	Noun	Adjective	Verb	Adverb
business activity	Yes	No	No	No
enterprise	Yes	No	No	No

As nouns, enterprise is a hypernym of business activity; that is, enterprise is a word with a broader meaning than business activity:

business activity: activity undertaken as part of a commercial enterprise
enterprise: a purposeful or industrious undertaking (especially one that requires effort or boldness)

Other hypernyms of business activity include endeavor, endeavour.

business activity (noun)	enterprise (noun)
activity undertaken as part of a commercial enterprise	a purposeful or industrious undertaking (especially one that requires effort or boldness)
	readiness to embark on bold new ventures
	an organization created for business ventures