whaleboat vs sea boat

whaleboat and sea boat both are nouns.

Word	Noun	Adjective	Verb	Adverb
whaleboat	Yes	No	No	No
sea boat	Yes	No	No	No

As nouns, sea boat is a hypernym of whaleboat; that is, sea boat is a word with a broader meaning than whaleboat:

whaleboat: a long narrow boat designed for quick turning and use in rough seas
sea boat: a boat that is seaworthy; that is adapted to the open seas

whaleboat (noun)	sea boat (noun)
a long narrow boat designed for quick turning and use in rough seas	a boat that is seaworthy; that is adapted to the open seas