combat ship vs military vehicle

combat ship and military vehicle both are nouns.

Word	Noun	Adjective	Verb	Adverb
combat ship	Yes	No	No	No
military vehicle	Yes	No	No	No

As nouns, military vehicle is a hypernym of combat ship; that is, military vehicle is a word with a broader meaning than combat ship:

Other hypernyms of combat ship include ship.

combat ship (noun)	military vehicle (noun)
a government ship that is available for waging war	vehicle used by the armed forces