backsliding vs relapsing

backsliding and relapsing both are nouns.

Word	Noun	Adjective	Verb	Adverb
backsliding	Yes	No	No	No
relapsing	Yes	No	No	No

As nouns, backsliding and relapsing are synonyms defined as:

Other synonyms of backsliding include lapse, lapsing, relapse, reversion, reverting.

backsliding (noun)	relapsing (noun)
a failure to maintain a higher state	a failure to maintain a higher state