combat ship vs ship

combat ship and ship both are nouns.

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

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

Other hypernyms of combat ship include military vehicle.

combat ship (noun)	ship (noun)
a government ship that is available for waging war	a vessel that carries passengers or freight