tower vs boat

tower and boat both are nouns.

Word	Noun	Adjective	Verb	Adverb
tower	Yes	No	Yes	No
boat	Yes	No	Yes	No

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

tower (noun)	boat (noun)
a structure taller than its diameter; can stand alone or be attached to a larger building	a small vessel for travel on water
anything that approximates the shape of a column or tower	a dish (often boat-shaped) for serving gravy or sauce
a powerful small boat designed to pull or push larger ships

tower (verb)	boat (verb)
appear very large or occupy a commanding position	ride in a boat on water