sex vs sexual desire

sex and sexual desire both are nouns.

Word	Noun	Adjective	Verb	Adverb
sex	Yes	No	Yes	No
sexual desire	Yes	No	No	No

sex (noun)	sexual desire (noun)
activities associated with sexual intercourse	a desire for sexual intimacy
the properties that distinguish organisms on the basis of their reproductive roles
all of the feelings resulting from the urge to gratify sexual impulses
either of the two categories (male or female) into which most organisms are divided

sex (verb)	sexual desire (verb)
tell the sex (of young chickens)
to evoke sexual feelings