criminology vs penology

criminology and penology both are nouns.

Word	Noun	Adjective	Verb	Adverb
criminology	Yes	No	No	No
penology	Yes	No	No	No

As nouns, penology is a hyponym of criminology; that is, penology is a word with a more specific, narrower meaning than criminology:

criminology: the scientific study of crime and criminal behavior and law enforcement
penology: the branch of criminology concerned with prison management and prisoner rehabilitation

Other hyponyms of criminology include poenology.

criminology (noun)	penology (noun)
the scientific study of crime and criminal behavior and law enforcement	the branch of criminology concerned with prison management and prisoner rehabilitation