expiration vs ending

expiration and ending both are nouns.

Word	Noun	Adjective	Verb	Adverb
expiration	Yes	No	No	No
ending	Yes	No	No	No

As nouns, ending is a hypernym of expiration; that is, ending is a word with a broader meaning than expiration:

Other hypernyms of expiration include end.

expiration (noun)	ending (noun)
the act of expelling air from the lungs	the act of ending something
euphemistic expressions for death	the end of a word (a suffix or inflectional ending or final morpheme)
a coming to an end of a contract period	the last section of a communication
	event whose occurrence ends something
	the point in time at which something ends