church building vs church

church building and church both are nouns.

Word	Noun	Adjective	Verb	Adverb
church building	Yes	No	No	No
church	Yes	No	Yes	No

As nouns, church building and church are synonyms defined as:

church building and church: a place for public (especially Christian) worship

church building (noun)	church (noun)
a place for public (especially Christian) worship	a service conducted in a house of worship
	a place for public (especially Christian) worship
	one of the groups of Christians who have their own beliefs and forms of worship
	the body of people who attend or belong to a particular local church

church building (verb)	church (verb)
	perform a special church rite or service for