icebreaker vs ship

icebreaker and ship both are nouns.

Word	Noun	Adjective	Verb	Adverb
icebreaker	Yes	No	No	No
ship	Yes	No	Yes	No

As nouns, ship is a hypernym of icebreaker; that is, ship is a word with a broader meaning than icebreaker:

icebreaker: a ship with a reinforced bow to break up ice and keep channels open for navigation
ship: a vessel that carries passengers or freight

icebreaker (noun)	ship (noun)
a beginning that relaxes a tense or formal atmosphere	a vessel that carries passengers or freight
a ship with a reinforced bow to break up ice and keep channels open for navigation