bulwark vs barrier

bulwark and barrier both are nouns.

Word	Noun	Adjective	Verb	Adverb
bulwark	Yes	No	Yes	No
barrier	Yes	No	No	No

As nouns, barrier is a hypernym of bulwark; that is, barrier is a word with a broader meaning than bulwark:

bulwark: a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away
barrier: a structure or object that impedes free movement

As nouns, barrier is a hypernym of bulwark; that is, barrier is a word with a broader meaning than bulwark:

bulwark (noun)	barrier (noun)
a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away	a structure or object that impedes free movement
an embankment built around a space for defensive purposes	any condition that makes it difficult to make progress or to achieve an objective
a fencelike structure around a deck	anything serving to maintain separation by obstructing vision or access

bulwark (verb)	barrier (verb)
defend with a bulwark