lovemaking vs sex activity

lovemaking and sex activity both are nouns.

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

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

lovemaking: sexual activities (often including sexual intercourse) between two people
sex activity: activities associated with sexual intercourse

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

lovemaking (noun)	sex activity (noun)
sexual activities (often including sexual intercourse) between two people	activities associated with sexual intercourse