separateness vs independency

separateness and independency both are nouns.

Word	Noun	Adjective	Verb	Adverb
separateness	Yes	No	No	No
independency	Yes	No	No	No

As nouns, independency is a hypernym of separateness; that is, independency is a word with a broader meaning than separateness:

Other hypernyms of separateness include independence.

separateness (noun)	independency (noun)
the quality of being not alike; being distinct or different from that otherwise experienced or known	freedom from control or influence of another or others
political independence
the state of being several and distinct