promiscuity vs sex activity

promiscuity and sex activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
promiscuity	Yes	No	No	No
sex activity	Yes	No	No	No

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

promiscuity: indulging in promiscuous (casual and indiscriminate) sexual relations
sex activity: activities associated with sexual intercourse

Other hypernyms of promiscuity include sex, sexual activity, sexual practice.

promiscuity (noun)	sex activity (noun)
indulging in promiscuous (casual and indiscriminate) sexual relations	activities associated with sexual intercourse