Technically speaking, it would be the "qualitative impairment." Of course there is much debate among the autistic community as to whether autism actually is a disorder or if it is just a neurological variant, and there is much debate as to what it means to be "impaired."
Personally I am not sure which side I fall on. I feel like if something is getting in one's way of having a good life, then maybe it can be considered a disorder. But there are of course different ways of living, and for some what brings happiness is not the same as it is for others. Objectively speaking (to the medical community, I guess) someone who can not live on their own and function in society in the same way that most people can are impaired in some way and thus have a disorder. If society functioned in a different way, however, some of these "impaired" people may be able to function better than the norm. But that is not the case for all autistics, either.
It gets even stickier if you consider, for example, a trait of extreme shyness, for example, which is not considered a disorder in itself, but can indeed impair a person's ability to socialize, socially network, and in our socially based world, likely it impairs them in moving forward in their career and in other areas of life.
So to be honest, I'm not sure how to answer your question. I think maybe on the more "extreme" end of the autistic spectrum it is more concrete to call it "disorder," where there are people who are in constant distress due to sensory overload, inability to communicate their needs, and so on. Maybe then if someone is in distress due to their traits and symptoms directly I would call it a disorder. What I mean is, if a person with Asperger's were in distress due to actual symptoms rather than due to the reaction and treatment within society, that would be to me disorder. If a person with Asperger's is perfectly happy until they have to venture out into the world and meet with poor treatment due to their differences, then I think that it is a much murkier area and it may or may not be a "disorder." It is also not really possible to entirely separate a person from their experiences since experience is part of what forms oneself, so to make the division between "it is my symptoms of Asperger's which distress me in social situations" and "it is because I have had bad experiences that I am distressed in social situations" is not always possible because those two aspects are likely intertwined in many people.
"I am I." - Ayanami Rei