actually they all belong to PDD/Autism Spectrum

PDD or pervasive developmental disorder is a behavioral disorder of speech, communication, social interaction, and repetitive type compulsive behavior. Autism is a form of PDD. There are five types of PDD's.

1. Childhood autism

2. Asperger's syndrome

3. Childhood disintegrative disorder

4. Rett's disease

5. PDD NOS (pervasive developmental disorder not otherwise specified)