narthex vs entrance hall

narthex and entrance hall both are nouns.

Word	Noun	Adjective	Verb	Adverb
narthex	Yes	No	No	No
entrance hall	Yes	No	No	No

As nouns, entrance hall is a hypernym of narthex; that is, entrance hall is a word with a broader meaning than narthex:

Other hypernyms of narthex include antechamber, anteroom, foyer, hall, lobby, vestibule.

narthex (noun)	entrance hall (noun)
a vestibule leading to the nave of a church	a large entrance or reception room or area
portico at the west end of an early Christian basilica or church