The psyc I'm currently taking my son to thinks that on top of the ADHD he either has Aspergers, or developmental delays. From what I've read/seen there doen't seem do be any difference. Is there?

Of course, aspergers is a high functioning version of autism and AD/HD is a specific neurological problem that deals with dopamine deficency in the prefrontal cortex.

There are similarities in that they are both seen as impairing the executive functions. At a closer look they are distinguishable. Asperger's is primarily a social disability, there is a lack of any intuitive social know how. ADD is impairment of attention in a variety of contexts, social, recreational, educational, and vocational, and presents itself in procrastination, disorganization, distraction, hunger for stimulation, etc. It's possible to have both conditions.

Developmental delays is a vague term and can refer to a wide range of issues.

OK, I think the wording on my post was a bit off. I know there is a difference between ADHD and Aspergers. What I was wondering is what (if any) is the difference between Aspergers and developmental delays. Is DD just one of those "catch all" things which translates medicaly into a shrug?

Aspergers is just one type of developmental delay. There are other types as well, like Downs Syndrome or Angelmen Syndrome.