junk vs boat

junk and boat both are nouns.

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

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

junk (noun)	boat (noun)
any of various Chinese boats with a high poop and lugsails	a small vessel for travel on water
the remains of something that has been destroyed or broken up	a dish (often boat-shaped) for serving gravy or sauce

junk (verb)	boat (verb)
dispose of (something useless or old)	ride in a boat on water