The main differences centre around the kind of learners you will be teaching. Whereas in the UK you will probably teach multilingual classes, when it comes to teaching abroad you will most likley teach monolingual groups. It’s not necessarily that one type of class is easier to teach than the other, just that there are different things for you to consider when preparing and teaching lessons in each case.
Timetable-wise, most of the students that you teach abroad will study part-time, perhaps once or twice per week. This may well be in evening classes. In the UK you are more likely to be teaching students who are learning intensively, and most probably full-time, during the day.
When it comes to students’ motivations for wanting to take English lessons, these also tend to differ according to where you teach. Students who are learning English in private language schools in the UK are often learning with a set goal in mind, whether this is in a professional or academic context. Anyone studying English for commercial reasons will be aiming to become proficient enough to be able to conduct business successfully in English. Anyone studying for academic reasons, often in order to get their English up to scratch so that they can embark on a degree course in an English-speaking country, will most likely be looking to sit either the Cambridge Proficiency or IELTS level 7 exam at the end of their course.
There is possibly a wider variety of reasons why people are learning when it comes to students who are learning English in their local language school abroad. Whilst there will also be students learning for business or academic purposes, albeit on a lightly less intensive basis, there will also be students who are learning simply for leisure, or for pleasure…in the more developed countries anyway.