country vs sea power

country and sea power both are nouns.

Word	Noun	Adjective	Verb	Adverb
country	Yes	No	No	No
sea power	Yes	No	No	No

As nouns, sea power is a hyponym of country; that is, sea power is a word with a more specific, narrower meaning than country:

country (noun)	sea power (noun)
a politically organized body of people under a single government	naval strength
the people who live in a nation or country	a nation that possesses formidable naval strength
the territory occupied by a nation
an area outside of cities and towns
a particular geographical region of indefinite boundary (usually serving some special purpose or distinguished by its people or culture or geography)