western vs Western world

western and Western world both are nouns.

Word	Noun	Adjective	Verb	Adverb
western	Yes	Yes	No	No
Western world	Yes	No	No	No

western (noun)	Western world (noun)
a sandwich made from a western omelet	the countries of (originally) Europe and (now including) North America and South America

western (adjective)	Western world (adjective)
relating to or characteristic of the western parts of the world or the West as opposed to the eastern or oriental parts
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