burn off vs exhaust

burn off is not a noun while exhaust is a noun.

Word	Noun	Adjective	Verb	Adverb
burn off	No	No	Yes	No
exhaust	Yes	No	Yes	No

As verbs, exhaust is a hypernym of burn off; that is, exhaust is a word with a broader meaning than burn off:

Other hypernyms of burn off include consume, deplete, eat, eat up, expend, run through, use, use up, wipe out.

burn off (noun)	exhaust (noun)
	system consisting of the parts of an engine through which burned gases or steam are discharged
	gases ejected from an engine as waste products

burn off (verb)	exhaust (verb)
clear land of its vegetation by burning it off	wear out completely
use up (energy)	eliminate (a substance)
	use up the whole supply of
	use up (resources or materials)
	deplete