expedience vs expediency

expedience and expediency both are nouns.

Word	Noun	Adjective	Verb	Adverb
expedience	Yes	No	No	No
expediency	Yes	No	No	No

As nouns, expedience and expediency are synonyms defined as:

expedience and expediency: the quality of being suited to the end in view

expedience (noun)	expediency (noun)
the quality of being suited to the end in view	the quality of being suited to the end in view
taking advantage of opportunities without regard for the consequences for others