post house vs hostel

post house and hostel both are nouns.

Word	Noun	Adjective	Verb	Adverb
post house	Yes	No	No	No
hostel	Yes	No	No	No

As nouns, hostel is a hypernym of post house; that is, hostel is a word with a broader meaning than post house:

Other hypernyms of post house include auberge, hostelry, inn, lodge.

post house (noun)	hostel (noun)
an inn for exchanging post horses and accommodating riders	inexpensive supervised lodging (especially for youths on bicycling trips)
	a hotel providing overnight lodging for travelers