What are the differences between Asperger's Syndrome and Schizoid Personality Disorder? They are specifically listed as two separate disorders in the ICD, but what are the differences between Asperger's Syndrome and Schizoid Personality Disorder? 

Since both result in a withdrawal from social situations, the two can seem quite similar to an outside observer; is there any accurate method used to distinguish between the two in a subject?
Schizoid personality disorder is characterized by a lack of interest in social relationships. However, with asperger syndrome, it's a limited empathy and understanding of other's situations. In other words, asperger syndrome deals with the inability to empathize while schizoid personality disorder deals with apathy toward other's emotions. Additionally, people with apserger syndrome tend to be less withdrawn than people with schizoid personality disorder. People who have asperger syndrome show repetitive behavior and interests, while schizoid personality disorder does not show this fixation toward repetitive behavior. Asperger syndrome is probably genetically linked somehow and is placed on the autism spectrum. However, schizoid personality disorder is not on the autism spectrum. I hope this response helped!