what is the difference between pdd and autism?

we have a 26mo old girl who people are starting to believe may have pdd or autism.  they are her speech pathologist anf early intervention corrdinator.  some of the thinks that all of us see is the need for sensation in every think she does if she isnt moving she is bitting her feet, or fingers, she also getds great joy out of making me yell she thinks it is great to pull my hair as hard as she can, she will also hit and kick us and then say ow
when she is swinging and jumping the higher the better and the faster.  when she gets upset she will bang her head into the wall and she has also started to do this when she is board as e=well know. one other thing is she will sometimes pull her hand up when she is excited and go nannaan.she never stops moving  and is very clingy to my husband and i she requires huge amount of touching like bear jugs and kisses, and she also likes to spin.  she does have sever language delays,cognition, and social delays as well? does it sound like autism or pdd perhaps sensoru integration disorder maybe?

[Kevin Kennedy, Ph.D.]

Dear Marie,

Autism is one type od Pervasive Developmental Disorder. In other words, PDD is a category of emotional disorders, and Autism is one particular type in this broad category.

Autism is characterized by qualitative impairment in social interaction, qualitative impairments in communication, and by restricted repetitive and stereotyped patterns of behavior, interests and activities. Prior to the age of three, delays or abnormal functioning is displayed in social interaction, language as used in social communication or in symbolic or imaginative play.