instance vs apology

instance and apology both are nouns.

Word	Noun	Adjective	Verb	Adverb
instance	Yes	No	Yes	No
apology	Yes	No	No	No

As nouns, apology is a hyponym of instance; that is, apology is a word with a more specific, narrower meaning than instance:

Other hyponyms of instance include excuse, exception, case in point, precedent, quintessence, sample, specimen.

instance (noun)	apology (noun)
an item of information that is typical of a class or group	a poor example
an occurrence of something	an expression of regret at having caused trouble for someone
	a formal written defense of something you believe in strongly

instance (verb)	apology (verb)
clarify by giving an example of