sexual vs gender

sexual is not a noun while gender is a noun.

Word	Noun	Adjective	Verb	Adverb
sexual	No	Yes	No	No
gender	Yes	No	No	No

sexual (noun)	gender (noun)
	the properties that distinguish organisms on the basis of their reproductive roles
	a grammatical category in inflected languages governing the agreement between nouns and pronouns and adjectives; in some languages it is quite arbitrary but in Indo-European languages it is usually based on sex or animateness

sexual (adjective)	gender (adjective)
having or involving sex
of or relating to or characterized by sexuality
involved in a sexual relationship