revitalization vs improvement

revitalization and improvement both are nouns.

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

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

Other hypernyms of revitalization include advance, betterment.

revitalization (noun)	improvement (noun)
bringing again into activity and prominence	the act of improving something
	a change for the better; progress in development
	a condition superior to an earlier condition