Stimming/stimulatory behaviour

I'm a bit confused about the differences between stimming,  tics, and habits. Some definitions suggest tics are involuntary, compulsive, and usually preceded by physical discomfort. But then, if stimming behaviour is done for comfort, and is often done without a person noticing they're doing, then surely the two are similar? I have several 'habits' so to speak, that could be seen as either. I clear my throat repetitively, or try to do it silently if in public, often clench my fingers, clicking my wrists and fingers, and have a habit of rubbing the skin on my face. I bite my tongue almost constantly, especially when stressed. As a kid I used to be pulled up for picking my skin or pulling faces.

I'm a bit confused about the differences between stimming,  tics, and habits. Some definitions suggest tics are involuntary, compulsive, and usually preceded by physical discomfort. But then, if stimming behaviour is done for comfort, and is often done without a person noticing they're doing, then surely the two are similar? I have several 'habits' so to speak, that could be seen as either. I clear my throat repetitively, or try to do it silently if in public, often clench my fingers, clicking my wrists and fingers, and have a habit of rubbing the skin on my face. I bite my tongue almost constantly, especially when stressed. As a kid I used to be pulled up for picking my skin or pulling faces.