sexual activity vs body process

sexual activity and body process both are nouns.

Word	Noun	Adjective	Verb	Adverb
sexual activity	Yes	No	No	No
body process	Yes	No	No	No

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

Other hypernyms of sexual activity include activity, bodily function, bodily process.

sexual activity (noun)	body process (noun)
activities associated with sexual intercourse	an organic process that takes place in the body