How did Leo Kanner distinguish autism from schizophrenia?

In 1943, psychiatrist Leo Kanner established autism as a distinct clinical syndrome, separating it from the concept of schizophrenia that had previously been associated with the term.12

While the term "autism" was originally coined in 1911 by Eugen Bleuler to describe a withdrawal into an inner world observed in patients with schizophrenia, Kanner provided a new, modern definition based on his clinical observations of 11 children. He identified a specific behavioral profile characterized by an inability to relate to people or situations in an "ordinary way" and an "anxiously obsessive desire for the maintenance of sameness". By documenting these unique patterns of affective contact, Kanner successfully distinguished this developmental condition from the psychotic symptoms associated with schizophrenia.132

It is important to note that Kanner later introduced the harmful and scientifically inaccurate "refrigerator mother" theory, which blamed parents for their children's condition; he eventually repudiated this theory and the term by the 1970s.3