spiritual world vs belief

spiritual world and belief both are nouns.

Word	Noun	Adjective	Verb	Adverb
spiritual world	Yes	No	No	No
belief	Yes	No	No	No

As nouns, belief is a hypernym of spiritual world; that is, belief is a word with a broader meaning than spiritual world:

spiritual world: a belief that there is a realm controlled by a divine spirit
belief: any cognitive content held as true

spiritual world (noun)	belief (noun)
a belief that there is a realm controlled by a divine spirit	any cognitive content held as true
	a vague idea in which some confidence is placed