backsliding vs lapsing

backsliding and lapsing both are nouns.

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

As nouns, backsliding and lapsing are synonyms defined as:

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

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