boat vs vessel

boat and vessel both are nouns.

Word	Noun	Adjective	Verb	Adverb
boat	Yes	No	Yes	No
vessel	Yes	No	No	No

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

Other hypernyms of boat include watercraft.

boat (noun)	vessel (noun)
a small vessel for travel on water	a craft designed for water transportation
a dish (often boat-shaped) for serving gravy or sauce	an object used as a container (especially for liquids)
	a tube in which a body fluid circulates

boat (verb)	vessel (verb)
ride in a boat on water