vessel vs iceboat

vessel and iceboat both are nouns.

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

As nouns, iceboat is a hyponym of vessel; that is, iceboat is a word with a more specific, narrower meaning than vessel:

vessel: a craft designed for water transportation
iceboat: a sailing vessel with runners and a cross-shaped frame; suitable for traveling over ice

vessel (noun)	iceboat (noun)
a craft designed for water transportation	a ship with a reinforced bow to break up ice and keep channels open for navigation
an object used as a container (especially for liquids)	a sailing vessel with runners and a cross-shaped frame; suitable for traveling over ice
a tube in which a body fluid circulates