descriptive vs linguistics

descriptive is not a noun while linguistics is a noun.

Word	Noun	Adjective	Verb	Adverb
descriptive	No	Yes	No	No
linguistics	Yes	No	No	No

descriptive (noun)	linguistics (noun)
	the scientific study of language
	the humanistic study of language and literature

descriptive (adjective)	linguistics (adjective)
of or relating to an approach to linguistic analysis that aims at the description of a language's forms, structures and usage
serving to describe or inform or characterized by description