A disability just means you can't do something that a typical person would be able to do in an average fashion. Anyone with AS has a disability, though to different degrees.
Permanent disability (I'm guessing you mean for SSI purposes because of your previous post) means permanently unable to work as judged by the standards of whatever organization is awarding you the money for said disability. If you were to get SSI on the basis of AS, that would be permanent, because Autism Spectrum Disorders cannot be cured. It does not mean that you are required to ALWAYS be on SSI, if you find a job that can accommodate you, just that they assume you are never going to get better. Some impairments under disability law are considered not permanent and are reevaluated more often after disability is awarded. For example Someone with depression would be re-evaluated every three years to verify their condition has not improved such that they can work, whereas someone with Autism would be evaluated every seven and pretty much rubber-stamped through the process, because it is seen as a permanent condition.