Tics aren't necessarily caused by tourettes, and some individuals experience them from other neurological issues. In fact, they are a less-common symptom of autism.
Tics differ from stims because stims are a response to a need for, well, stimulation. They are sometimes intentional and sometimes not, and are used to express emotion, to lessen anxiety or boredom, or to satisfy the craving for a certain sensory input. Tics, on the other hand, are uncontrollable, and are more akin to twitches than stims.
For instance, when I am anxious or frustrated, I will pace very quickly back and forth. This is a stim, because, though I am not thinking about it, I am expressing my emotions and attempting to physically release my stress. However, I experience a tic which involves the muscles in my neck randomly spasming and causing my head to jerk to the left, sometimes violently. The first, though not exactly "controllable," has a clear source and execution, unlike the latter.
I hope this makes sense.
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Beep beep, all aboard the idiot wagon.
End ★ 20 ★ Male ★ Capricorn ★ ISTJ-T