Experts today generally agree that there is no single mental condition called autism. Rather, there is a spectrum of autistic disorders, with different forms of autism taking different positions on this spectrum. But within certain circles of the autism/AS community, this concept of a "spectrum" is being severely questioned. If differences in development are purely a function of differential acquisition of skills, then attempting to distinguish between "degrees of severity" may be dangerously misleading. A person may be subjected to unrealistic expectations, or even denied life-saving services, solely on the basis of very superficial observations made by others in the community.
In the 1940s, Leo Kanner and Hans Asperger, working independently in the United States and Austria, identified essentially the same population, Asperger's group being perhaps more "socially functional" than Kanner's as a whole. Some of Kanner's originally identified autistic children might today get an Asperger's syndrome diagnosis, and vice versa. It is a mistake to say that a "Kanner autistic" is a child who sits and rocks and does not communicate. Kanner's study subjects were all along the spectrum.
Traditionally, Kannerian autism is characterized by significant cognitive and communicative deficiencies, including delays in or lack of language. Often it will be clear that these people do not function normally. An individual with Asperger's on the other hand will not show delays in language. It is a more subtle disorder and affected individuals will often only appear to be eccentric.
Researchers are grappling with the problem of how to divide up the spectrum. There are many potential definitional divisions: autistics who speak versus those who do not; autistics with seizures versus those without; autistics with more "stereotypical behaviors" versus those with fewer; and so forth. Some are trying to identify genes associated with these traits as a way to make logical groupings. Eventually, one may hear about autistics with or without the HOXA 1 gene, with or without changes to chromosome 15, etc.
Some clinicians believe that communicative and/or cognitive deficiencies are so essential to the concept of autism that they prefer to consider Asperger's as a separate condition altogether from autism. This opinion is a minority one. Uta Frith (an early researcher of Kannerian autism) has written that people with Asperger's seem to have more than a touch of autism to them. Others, such as Lorna Wing and Tony Attwood, share in Frith's assessment. Dr. Sally Ozonoff, of the University of California at Davis's MIND institute, argues that there should be no dividing line between "high-functioning" autism and Asperger's, and that the fact that some individuals do not start to produce speech until a later age is no reason to divide the two groups, as they are identical in the way they need to be treated. Asperger's syndrome and other forms of autism are often grouped together in a Pervasive Developmental Disorder family.
Read more about Possible causes and origins.
