naval blockade vs encirclement

naval blockade and encirclement both are nouns.

Word	Noun	Adjective	Verb	Adverb
naval blockade	Yes	No	No	No
encirclement	Yes	No	No	No

As nouns, encirclement is a hypernym of naval blockade; that is, encirclement is a word with a broader meaning than naval blockade:

naval blockade: the interdiction of a nation's lines of communication at sea by the use of naval power
encirclement: a war measure that isolates some area of importance to the enemy

Other hypernyms of naval blockade include blockade.

naval blockade (noun)	encirclement (noun)
the interdiction of a nation's lines of communication at sea by the use of naval power	a war measure that isolates some area of importance to the enemy