combust vs light up

combust and light up both are verbs.

Word	Noun	Adjective	Verb	Adverb
combust	No	No	Yes	No
light up	No	No	Yes	No

As verbs, light up is a hyponym of combust; that is, light up is a word with a more specific, narrower meaning than combust:

Other hyponyms of combust include blow out, catch.

combust (verb)	light up (verb)
undergo combustion	introduce light into
get very angry and fly into a rage	begin to smoke
cause to become violent or angry	become clear
start to burn or burst into flames	start to burn with a bright flame
cause to burn or combust	ignite