arousal vs sexual activity

arousal and sexual activity both are nouns.

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

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

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

arousal (noun)	sexual activity (noun)
the act of arousing	activities associated with sexual intercourse
mutual sexual fondling prior to sexual intercourse
awakening from sleep
a state of heightened physiological activity