iceboat vs watercraft

iceboat and watercraft both are nouns.

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

As nouns, watercraft is a hypernym of iceboat; that is, watercraft is a word with a broader meaning than iceboat:

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

Other hypernyms of iceboat include vessel.

iceboat (noun)	watercraft (noun)
a ship with a reinforced bow to break up ice and keep channels open for navigation	a craft designed for water transportation
a sailing vessel with runners and a cross-shaped frame; suitable for traveling over ice	skill in the management of boats