on fire vs aflare

on fire and aflare both are adjectives.

Word	Noun	Adjective	Verb	Adverb
on fire	No	Yes	No	No
aflare	No	Yes	No	No

As adjectives, on fire and aflare are synonyms defined as:

Other synonyms of on fire include ablaze, afire, aflame, alight.

on fire (adjective)	aflare (adjective)
lighted up by or as by fire or flame	lighted up by or as by fire or flame
	streaming or flapping or spreading wide as if in a current of air