craving vs appetency

craving and appetency both are nouns.

Word	Noun	Adjective	Verb	Adverb
craving	Yes	No	No	No
appetency	Yes	No	No	No

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

Other hyponyms of craving include appetence, appetite, addiction.

craving (noun)	appetency (noun)
an intense desire for some particular thing	a feeling of craving something