How does one distinguish between an autistic shutdown vs a dissociative episode?
In my case it‘s sometimes quite similar too! Also my therapist said, that e.g. derealisation/depersonalisation can also be „symptoms“ of a overload…
Dissociation is always a bodys attempt to protect yourself from some emotion.
For example at a „real“ dissociative episode I‘m completely zoned out, I don‘t remember anything afterwards of the time and I‘m not responding during the episode to somebody talking to me! I mostly notice it before it happens, because I start „zoning out“, staring into the emptiness, not thinking anything at all anymore…
(Derealisation &) Depersonalisation are often happening in very stressfull situations and my body just seems to go into a „pause-mode“.
I‘m functioning and notice everything around me, but feeling like i‘m not belonging to my body… Strange feeling at first, but I‘ve gotten used to it sadly…
Shutdowns in my case still have some „bodymovement“ e.g. I „rock“ back and forth, still thinking and notice everything around me, but I need complete darkness & silence… I could do stuff, but have absolutely no more energy to do so…
Maybe imagine it as a phone:
Shutdown = when your Phone is „overheated“, you can‘t touch it, it needs to cool down and a pause from operating it. But still works in the Background
Dissociation is in my opinon when your cellphone no longer reacts to anything, but is still on. Like it was functioning with a lot of apps, but then you open another app and nothing works anymore. You can‘t press any buttons etc, just wait until it works again…
Maybe that helps as a description for you question?