aberration vs abnormalcy

aberration and abnormalcy both are nouns.

Word	Noun	Adjective	Verb	Adverb
aberration	Yes	No	No	No
abnormalcy	Yes	No	No	No

As nouns, abnormalcy is a hypernym of aberration; that is, abnormalcy is a word with a broader meaning than aberration:

aberration: a state or condition markedly different from the norm
abnormalcy: an abnormal physical condition resulting from defective genes or developmental deficiencies

Other hypernyms of aberration include abnormality.

aberration (noun)	abnormalcy (noun)
an optical phenomenon resulting from the failure of a lens or mirror to produce a good image	an abnormal physical condition resulting from defective genes or developmental deficiencies
a disorder in one's mental state
a state or condition markedly different from the norm