I'm diagnosed autistic and they said they were sure I also have ADHD and should pursue a diagnosis (I havent yet) , I do feel I have textbook "AUDHD" traits, I crave routine but can't stick to it etc
I used to always think obsessive things were my autism, but I don't think it's that clear cut.
ADHD in my experience isn't a defect of attention, it's too much of it and an inability to focus it (deficit in control) which can lead to being totally unable to focus on something, or in contrast totally unable to focus on anything but that thing, usually because I'm enjoying it.
Autism I believe shows the same behaviour but the motivation is more driven by either fear of changing to something else, inertia, demand avoidance, absolute obsession on completion etc.
They may just actually be the same thing entirely, as they do seem to be suggesting that maybe it's part of the same mechanism/on the same spectrum.
Depends what you are referring to really. Compulsive behaviour isn't in the diagnostic criteria for either. Some autistic people really rely on routines and some of this can become compulsive. People with ADHD can become perfectionists so again some of this behaviour can become compulsive.
If it is a range of compulsive behaviours that are having a significant impact on life then it would be more likely to be OCD.
