In the Psycho-Bible, AS (along with Autism) is listed as a Pervasive Developmental Disorder (PDD) under the heading of Information-Exchange Disorders (IED). In English that means that AS and Autism *are* PDDs, just specified ones. Someone with a dx of PDD-NOS (Not Otherwise Specified) is someone who has enough diagnostical traits to be placed on the Autism Spectrum but thier individual profile does not match a specified catagory.
Simply put, PDD-NOS is the 'catch-all' dx that allows people to maintain their mental health records and get services they may need. There are many flaws with this system of dxing, but at the moment it's what we have to work with.
his language skills are significantly delayed, and he literally recites video scriptshe has no special obsessions with particular topics (no "little prof" syndrome)he doesn't have a lot of trouble expressing or understanding body languagehis academic skills are exactly on grade level (no special aptitudes or difficulties)
I have a great book called the Parent's Guide to Aspergers and HFA (can't remember author!), but it describes similarities and differences in detail.
BUT (important but) there's really very little difference in treatment. So... unless it's just for your own interest, it kinda doesn't really matter!