Do teachers ,and English teachers precisely,differ from each others?could a professional Tunisian English teacher be professional as well in Qatar?

It's a god question.

I don't think there's a big difference between an English Teacher and a teacher of another subject. Of course, there are differences in teaching style; however, it does not count to be a good deal. 

Certainly, a Tunisian can be a good teacher not only Qatar,  but anywhere of the world too, as far as teaching and learning is concerned, but I'm sorry to say whether the Europeans will ever allow this happen in their land....