square-rigger vs sailing ship

square-rigger and sailing ship both are nouns.

Word	Noun	Adjective	Verb	Adverb
square-rigger	Yes	No	No	No
sailing ship	Yes	No	No	No

As nouns, sailing ship is a hypernym of square-rigger; that is, sailing ship is a word with a broader meaning than square-rigger:

square-rigger: a square-rigged sailing ship
sailing ship: a vessel that is powered by the wind; often having several masts

Other hypernyms of square-rigger include sailing vessel.

square-rigger (noun)	sailing ship (noun)
a square-rigged sailing ship	a vessel that is powered by the wind; often having several masts