sailboat vs sailing vessel

sailboat and sailing vessel both are nouns.

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

As nouns, sailing vessel is a hypernym of sailboat; that is, sailing vessel is a word with a broader meaning than sailboat:

sailboat: a small sailing vessel; usually with a single mast
sailing vessel: a vessel that is powered by the wind; often having several masts

Other hypernyms of sailboat include sailing ship.

sailboat (noun)	sailing vessel (noun)
a small sailing vessel; usually with a single mast	a vessel that is powered by the wind; often having several masts