ateleiosis vs infantilism

ateleiosis and infantilism both are nouns.

Word	Noun	Adjective	Verb	Adverb
ateleiosis	Yes	No	No	No
infantilism	Yes	No	No	No

As nouns, infantilism is a hypernym of ateleiosis; that is, infantilism is a word with a broader meaning than ateleiosis:

ateleiosis: a form of infantilism characterized by physical underdevelopment but normal intelligence
infantilism: an abnormal condition in which an older child or adult retains infantile characteristics

ateleiosis (noun)	infantilism (noun)
a form of infantilism characterized by physical underdevelopment but normal intelligence	infantile behavior in mature persons
	an abnormal condition in which an older child or adult retains infantile characteristics