pairing vs sexual activity

pairing and sexual activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
pairing	Yes	No	No	No
sexual activity	Yes	No	No	No

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

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

pairing (noun)	sexual activity (noun)
the act of pairing a male and female for reproductive purposes	activities associated with sexual intercourse
the act of grouping things or people in pairs