homosexuality vs sex activity

homosexuality and sex activity both are nouns.

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

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

homosexuality: a sexual attraction to (or sexual relations with) persons of the same sex
sex activity: activities associated with sexual intercourse

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

homosexuality (noun)	sex activity (noun)
a sexual attraction to (or sexual relations with) persons of the same sex	activities associated with sexual intercourse