vessel vs ice yacht

vessel and ice yacht both are nouns.

Word	Noun	Adjective	Verb	Adverb
vessel	Yes	No	No	No
ice yacht	Yes	No	No	No

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

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

vessel (noun)	ice yacht (noun)
a craft designed for water transportation	a sailing vessel with runners and a cross-shaped frame; suitable for traveling over ice
an object used as a container (especially for liquids)
a tube in which a body fluid circulates