One of the most common mistakes made about autism is that Asperger's Syndrome and high functioning autism are the same thing. Many parents struggle with this problem because there is so much information out there that uses the two terms interchangeably. There are many crossover symptoms between Asperger's Syndrome and high functioning autism which can make it very challenging to tell the difference between the two. Furthermore, many doctors and scientists differ in their definitions of the two disorders.

High functioning autism is an unofficial designation for people who have autism but whose symptoms are not severe. High functioning autistic children have an average or above-average intelligence level and will generally maintain an adequate vocabulary. However their learning comprehension is typically behind other children at the same age. Furthermore, high functioning autistic children will generally not express much emotional detail in their speech, and struggle with interpreting non-verbal cues.

There is no solid line between the diagnosis of low functioning and high functioning autism. Though some doctors use an IQ score as an indicator to help with the diagnosis, the function level of autism is not based on IQ alone. There are also elements of language processing, behavioral elements, and other non-verbal details, which must be considered above and beyond measurable intelligence levels. Furthermore, standard IQ testing is typically inaccurate for autistic children as the testing itself may involve skills with which an autistic child struggles.

Whether high or low functioning, autism will typically present in around the age of two years old with a sudden regression or presentation of autistic symptoms.

On the other hand, Asperger's Syndrome is a separate autism spectrum disorder. Children with Asperger's Syndrome struggle with social interactions and restrictions, and tend to have intensely narrow interests in subjects and activities. However, unlike with autism - even high functioning autism - there is no cognitive development or language delay. Though language may be used atypically and motor skills may be clumsy at times, their development is normal.

Asperger's Syndrome will typically present in children at about the age of three. Brain imaging has shown structural and functional differences within certain brain regions among children without autism spectrum disorders, children with Asperger's Syndrome, and children who are high functioning autistics.

Children with Asperger's Syndrome often fail to display empathy in their behaviors. It is social interaction where these children face their deepest challenges. Many struggle or fail to develop friendships, don't take pleasure in achievements or spontaneous activities with others, lack in emotional and social reciprocity, and have diminished non-verbal communication behaviors such as facial expressions, postures, eye contact, and overall gestures.

However, children with classic autism (even those who are high functioning), Asperger's Syndrome children will not typically withdraw from other people. In fact, even if they are awkward in their method, they will often approach others and begin a discussion. It is conversation where their struggle may occur, as a discussion for a child with Asperger's Syndrome may simply consist of a long-winded single-sided speech about something the child truly enjoys, without any need for contribution from the other people present.