mating vs sex activity

mating and sex activity both are nouns.

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

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

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

mating (noun)	sex activity (noun)
the act of pairing a male and female for reproductive purposes	activities associated with sexual intercourse