foreplay vs sex activity

foreplay and sex activity both are nouns.

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

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

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

foreplay (noun)	sex activity (noun)
mutual sexual fondling prior to sexual intercourse	activities associated with sexual intercourse