cabin cruiser vs powerboat

cabin cruiser and powerboat both are nouns.

Word	Noun	Adjective	Verb	Adverb
cabin cruiser	Yes	No	No	No
powerboat	Yes	No	No	No

As nouns, powerboat is a hypernym of cabin cruiser; that is, powerboat is a word with a broader meaning than cabin cruiser:

cabin cruiser: a large motorboat that has a cabin and plumbing and other conveniences necessary for living on board
powerboat: a boat propelled by an internal-combustion engine

Other hypernyms of cabin cruiser include motorboat.

cabin cruiser (noun)	powerboat (noun)
a large motorboat that has a cabin and plumbing and other conveniences necessary for living on board	a boat propelled by an internal-combustion engine