An infantile is not at all the same as a human child. An infantile lags behind the average statistical norm of development, a person-child — from the possibility of becoming an adult. Manifestations of a child’s position and childish traits in an adult are not a pathology, but a cultural norm of modern society.
A child-man is a familiar norm for us, since there are not many mentally adult people around us. Every second person around us is a child, when it is not clear why he is offended, swears for no reason, sticks to the TV and buys bright and tasty, and not necessary and healthy.
Infantile is going beyond the limits of the norm, a variant of some pathology.