The s in « s’appelle » is the (reflexive) pronoun « se », whereas the t in « t’appelles » is « te ». It’s the difference between “what does he call himself” and “what do you call yourself.”
The Quebec thing would be « comment tu t’appelles-tu ? » where the second « tu » is a question marker, not a pronoun (but also I don’t think I’ve ever heard that form used for this question).
The s in « s’appelle » is the (reflexive) pronoun « se », whereas the t in « t’appelles » is « te ». It’s the difference between “what does he call himself” and “what do you call yourself.”
The Quebec thing would be « comment tu t’appelles-tu ? » where the second « tu » is a question marker, not a pronoun (but also I don’t think I’ve ever heard that form used for this question).