antecedency vs anteriority

antecedency and anteriority both are nouns.

Word	Noun	Adjective	Verb	Adverb
antecedency	Yes	No	No	No
anteriority	Yes	No	No	No

As nouns, antecedency and anteriority are synonyms defined as:

Other synonyms of antecedency include antecedence, precedence, precedency, priority.

antecedency (noun)	anteriority (noun)
preceding in time	the quality of being in front or (in lower animals) toward the head
	preceding in time