using up vs burnup

using up and burnup both are nouns.

Word	Noun	Adjective	Verb	Adverb
using up	Yes	No	No	No
burnup	Yes	No	No	No

As nouns, burnup is a hyponym of using up; that is, burnup is a word with a more specific, narrower meaning than using up:

using up (noun)	burnup (noun)
the act of consuming something	the amount of fuel used up (as in a nuclear reactor)
	a high-speed motorcycle race on a public road