There are two differences between the proposed constructions:
Using tu or vous
I suppose this is not the problem and won't even stop on this. If this is a problem, I suppose a separate question would be better.
Order of the words
As Casey said, both proposed structures are used but both fall outside of the grammar rule book we learned as children. Below is a summary of all constructions I know for this question.
Please note these constructions can be applied to any question, hence another totally unrelated example for each.
Informal, almost only oral
Affimative proposition + interrogative pronoun/adverb + "_ ?_"
- Tu t'appelles comment ? / Vous vous appelez comment ?
- Tu es qui ? / Vous êtes qui ?
Informal, common at oral
Interrogative pronoun/adverb + affimative proposition + "_ ?_"
- Comment tu t'appelles ? / Comment vous vous appelez ?
- Qui tu es ? / Qui vous êtes ?
Interrogative pronoun/adverb + "est-ce que" + affimative proposition + "_ ?_"
- Comment est-ce que tu t'appelles ? / Comment est-ce que vous vous appelez ?
- Qui est-ce que tu es ? / Qui est-ce que vous êtes ?
Interrogative pronoun/adverb + interrogative proposition (subject inversion) + "_ ?_"
- Comment t'appelles-tu ? / Comment vous appelez-vous ?
- Qui es-tu ? / Qui êtes-vous ?
1. Though more formal, this may seem more natural to a native than the "common" construction depending on the question. "Qui est-ce que tu es ?" for instance, though grammatically correct, is almost never used, while "Qui es-tu ?" is standard. Natives will understand any of the above constructions nonetheless.
Thanks for noting this answer is largely based on Casey's and jlliagre's answer because I think this view is interesting.