strengthener vs backing

strengthener and backing both are nouns.

Word	Noun	Adjective	Verb	Adverb
strengthener	Yes	No	No	No
backing	Yes	No	No	No

As nouns, backing is a hyponym of strengthener; that is, backing is a word with a more specific, narrower meaning than strengthener:

Other hyponyms of strengthener include mount, brace, bracing, brace, safety arch.

strengthener (noun)	backing (noun)
a device designed to provide additional strength	the act of providing approval and support
	something forming a back that is added for strengthening
	financial resources provided to make some project possible