brig vs penal institution

brig and penal institution both are nouns.

Word	Noun	Adjective	Verb	Adverb
brig	Yes	No	No	No
penal institution	Yes	No	No	No

As nouns, penal institution is a hypernym of brig; that is, penal institution is a word with a broader meaning than brig:

brig: a penal institution (especially on board a ship)
penal institution: an institution where persons are confined as punishment and to protect the public

Other hypernyms of brig include penal facility.

brig (noun)	penal institution (noun)
a penal institution (especially on board a ship)	an institution where persons are confined as punishment and to protect the public
two-masted sailing vessel square-rigged on both masts