Lisa Friedman, Inclusive Educator, Religious School Director, writer & speaker
Autism is not a single disorder, but a spectrum of closely-related disorders with a shared core of symptoms. It is a way to explain that no two children with autism will demonstrate the same behaviors and/or characteristics. There is a wide degree of variation in the way autism affects people.
Here is an article with additional information about the various terms, symptoms, behaviors, etc: http://www.helpguide.org/articles/autism/autism-spectrum-disorders.html