southwestern vs western

southwestern is not a noun while western is a noun.

Word	Noun	Adjective	Verb	Adverb
southwestern	No	Yes	No	No
western	Yes	Yes	No	No

southwestern (noun)	western (noun)
	a sandwich made from a western omelet

southwestern (adjective)	western (adjective)
situated in or oriented toward the southwest	relating to or characteristic of the western parts of the world or the West as opposed to the eastern or oriental parts
of a region of the United States generally including New Mexico, Arizona, Texas, California, and sometimes Nevada, Utah, Colorado	of or characteristic of regions of the United States west of the Mississippi River
	lying toward or situated in the west
	of wind; from the west