sexual activity vs usage

sexual activity and usage both are nouns.

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

sexual activity (noun)	usage (noun)
activities associated with sexual intercourse	the act of using
	accepted or habitual practice
	the customary manner in which a language (or a form of a language) is spoken or written