Mild disabilities include learning disability, high-functioning autism, Asperger syndrome, emotional disturbances, and ADHD. Individuals with mild disabilities have difficulty with cognition, language, social skills, physical abilities, and so forth.
Pervasive Developmental Disorder (PDD) refers a group of disorders characterized by socialization and communication difficulties. Depending on the types of PDD, their abilities, intelligence, and behaviors significantly vary. Examples of PDD inclues autism, Asperger syndrome, and Rett syndrome.
Expected developmental stages differ by age.
The attributes above are the features compared to same age peers.