lapsing vs relapsing

lapsing and relapsing both are nouns.

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

As nouns, lapsing and relapsing are synonyms defined as:

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

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