ateliosis vs infantilism

ateliosis and infantilism both are nouns.

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

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

ateliosis: 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

ateliosis (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