exhaust vs burn off

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

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

As verbs, burn off is a hyponym of exhaust; that is, burn off is a word with a more specific, narrower meaning than exhaust:

exhaust (noun)	burn off (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

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