proficiency vs competency

proficiency and competency both are nouns.

Word	Noun	Adjective	Verb	Adverb
proficiency	Yes	No	No	No
competency	Yes	No	No	No

As nouns, competency is a hypernym of proficiency; that is, competency is a word with a broader meaning than proficiency:

proficiency: the quality of having great facility and competence
competency: the quality of being adequately or well qualified physically and intellectually

Other hypernyms of proficiency include competence.

proficiency (noun)	competency (noun)
the quality of having great facility and competence	the quality of being adequately or well qualified physically and intellectually
skillfulness in the command of fundamentals deriving from practice and familiarity