I don't necessarily think they are all on the exactly the same field, since the lines do blur, but it takes a certain accumulation to make up autism. Personally, I was diagnosed with ADHD very early in life, and then a few years ago told I also have AS. Many of us on the spectrum suffer from sensory and attentional issues because those are large parts of autism. So, many with autism could also be diagnosed with other things as well.

I do agree that all in all, the specifics are rather unimportant. What is important is understanding your kid's problems and coming up with strategies for helping them. Too much time is spent dwelling on figuring out the exact condition, when more time should be sent helping them. It saddens me to know that things haven't changed much since I was a kid and that doctors still over prescribe medications kids don't really need.

LaneSensorina: even though a "lack of empathy" is considered to be a diagnostic component of ASDs, it's actually been determined by the autism community itself that it isn't that simple. Some time ago, when I was more active on Psych Forums, this very question came up and most, if not everyone, said we do have empathy. In fact, it seems as though a lot of us have too much empathy. The problem is, we have a hard time expressing it. We feel it, we just don't know what to do about it. I always get really uncomfortable when people are upset around me. I don't like they are upset, I want to help them, I may even feel really bad for them... I just often don't know what to do/say and I can see how that can come off seeming like I have little or no empathy.

Edit: oh, seems as though I am now one post away from being a Regular. :O Most go find something to answer!