basilica vs church building

basilica and church building both are nouns.

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

As nouns, church building is a hypernym of basilica; that is, church building is a word with a broader meaning than basilica:

basilica: an early Christian church designed like a Roman basilica; or a Roman Catholic church or cathedral accorded certain privileges
church building: a place for public (especially Christian) worship

Other hypernyms of basilica include church.

basilica (noun)	church building (noun)
a Roman building used for public administration	a place for public (especially Christian) worship
an early Christian church designed like a Roman basilica; or a Roman Catholic church or cathedral accorded certain privileges