revival vs improvement

revival and improvement both are nouns.

Word	Noun	Adjective	Verb	Adverb
revival	Yes	No	No	No
improvement	Yes	No	No	No

As nouns, improvement is a hypernym of revival; that is, improvement is a word with a broader meaning than revival:

Other hypernyms of revival include advance, betterment.

revival (noun)	improvement (noun)
bringing again into activity and prominence	the act of improving something
an evangelistic meeting intended to reawaken interest in religion	a change for the better; progress in development
	a condition superior to an earlier condition