boat vs tower

boat and tower both are nouns.

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

As nouns, tower is a hyponym of boat; that is, tower is a word with a more specific, narrower meaning than boat:

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

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