armed service vs navy

armed service and navy both are nouns.

Word	Noun	Adjective	Verb	Adverb
armed service	Yes	No	No	No
navy	Yes	No	No	No

As nouns, navy is a hyponym of armed service; that is, navy is a word with a more specific, narrower meaning than armed service:

armed service: a force that is a branch of the armed forces
navy: an organization of military vessels belonging to a country and available for sea warfare

Other hyponyms of armed service include army, ground forces, regular army, naval forces, coastguard, Marines, air force, airforce.

armed service (noun)	navy (noun)
a force that is a branch of the armed forces	a dark shade of blue
	an organization of military vessels belonging to a country and available for sea warfare