The distinction I’ve found other people say is stims are voluntary, tics are involuntary. I think this probably comes from people with one condition not wanting to step on the toes of another, to stay in their lanes. Which is super fair and admirable, I just think these lanes are reeeeeaaaaallly close and they seem to overlap.
What I’d say about this distinction is voluntary/involuntary is a false binary, things are much more interesting than that!

