acephalism vs abnormalcy

acephalism and abnormalcy both are nouns.

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

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

acephalism: absence of the head (as in the development of some monsters)
abnormalcy: an abnormal physical condition resulting from defective genes or developmental deficiencies

Other hypernyms of acephalism include abnormality.

acephalism (noun)	abnormalcy (noun)
absence of the head (as in the development of some monsters)	an abnormal physical condition resulting from defective genes or developmental deficiencies