self-justification vs alibi

self-justification and alibi both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-justification	Yes	No	No	No
alibi	Yes	No	Yes	No

As nouns, self-justification and alibi are synonyms defined as:

self-justification and alibi: a defense of some offensive behavior or some failure to keep a promise etc.

Other synonyms of self-justification include exculpation, excuse.

self-justification (noun)	alibi (noun)
a defense of some offensive behavior or some failure to keep a promise etc.	(law) a defense by an accused person purporting to show that he or she could not have committed the crime in question
	a defense of some offensive behavior or some failure to keep a promise etc.

self-justification (verb)	alibi (verb)
	exonerate by means of an alibi