backup vs backing

backup and backing both are nouns.

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

As nouns, backup and backing are synonyms defined as:

Other synonyms of backup include championship, patronage.

backup (noun)	backing (noun)
the act of providing approval and support	the act of providing approval and support
(computer science) a copy of a file or directory on a separate storage device	something forming a back that is added for strengthening
a musical part (vocal or instrumental) that supports or provides background for other musical parts	financial resources provided to make some project possible
someone who takes the place of another (as when things get dangerous or difficult)
an accumulation caused by clogging or a stoppage