blockhouse vs stronghold

blockhouse and stronghold both are nouns.

Word	Noun	Adjective	Verb	Adverb
blockhouse	Yes	No	No	No
stronghold	Yes	No	No	No

As nouns, stronghold is a hypernym of blockhouse; that is, stronghold is a word with a broader meaning than blockhouse:

blockhouse: a stronghold that is reinforced for protection from enemy fire; with apertures for defensive fire
stronghold: a strongly fortified defensive structure

Other hypernyms of blockhouse include fastness.

blockhouse (noun)	stronghold (noun)
a stronghold that is reinforced for protection from enemy fire; with apertures for defensive fire	a strongly fortified defensive structure