What is the difference between autism itself and autism spectrum?

Autism: ASD or autism spectrum disorder is a continum of diagnoses. An easy way to think of it is to imagine a number between 1-100. The severity of symptoms makes the diagnosis on a scale of 1-100. Aspergers is an asd, but so is autism. Intervention is based on what services are needed.

Quite a bit: Traditionally autism was used to referred to patients with severe deficits in communication and social interactions which often kept them in their own world and without meaningful verbal language. Now we recognize there is a spectrum of patients which includes the classic autistic patients but also a variety of patients who have less dramatic difficulties but still enough to impact functioning.