night porter vs ostiary

night porter and ostiary both are nouns.

Word	Noun	Adjective	Verb	Adverb
night porter	Yes	No	No	No
ostiary	Yes	No	No	No

As nouns, ostiary is a hypernym of night porter; that is, ostiary is a word with a broader meaning than night porter:

Other hypernyms of night porter include door guard, doorkeeper, doorman, gatekeeper, hall porter, porter.

night porter (noun)	ostiary (noun)
a porter on duty during the night	someone who guards an entrance
	the lowest of the minor Holy Orders in the unreformed Western Church but now suppressed by the Roman Catholic Church