sailing ship vs sailing vessel

sailing ship and sailing vessel both are nouns.

Word	Noun	Adjective	Verb	Adverb
sailing ship	Yes	No	No	No
sailing vessel	Yes	No	No	No

As nouns, sailing ship and sailing vessel are synonyms defined as:

sailing ship and sailing vessel: a vessel that is powered by the wind; often having several masts

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