aleja commented on dienasgramata's post:

In the current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), the most significant difference between Autistic Disorder (Kanner's) and Asperger's syndrome is that a diagnosis of the former includes the observation of "delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years: (1) social interaction, (2) language as used in social communication, or (3) symbolic or imaginative play" [2], while a diagnosis of Asperger's syndrome observes "no clinically significant delay" in these areas. [3]

Whilst the DSM-IV does not include level of intellectual functioning in the diagnosis, the fact that those with Asperger's syndrome tend to perform better than those with Kanner's autism has produced a popular conception that Asperger's syndrome is synonymous with "higher-functioning autism," or that it is a lesser disorder than autism.