How different is it to teach English to students of the same mother tongue(e.g. Arab) as compared to students of various cultures?

It varies, but I dare to say that when students share the mother tongue, they often rely on it for communication. Since "necessity is the mother of invention", when they do not share the mother tongue, the only way to communicate is in English.

I agreed but. ( Arbe) is universal because this one is the ADAM is use after  DEATH so ARABE IS NATURAL......... 

English is a language which has great reach and influence; it is taught all over the world under many circumstances. In English-speaking countries, English language teaching has essentially evolved in two broad directions: instruction for people who intend to live there and for those who do not. These divisions have grown firmer as the instructors of these two "industries" have used different terminology, followed distinct training qualifications, formed separate professional associations, and so on. Crucially, these two arms have very different funding structures, public in the former and private in the latter, and to some extent this influences the way schools are established and classes are held. Matters are further complicated by the fact that the United States and the United Kingdom, both major engines of the language, describe these categories in different terms