Hi,
I am new but I believe the difference becomes what are the goal and objectives of the class. For example, I am teaching English for Special Purposes (ESP) specializing in medical purposes for doctors and their students (Ss). I will suggest that you may want to visit a web site I found,
Arlyn Freed's ESL/EFL Resources at Arlyn Freed's ESL/EFL English for Specific Purposes.
It's almost schizophrenic
because I have to remember that first of all I am teaching EFL and not medicine. LOL! (Lots of Laughs)
Hope this helps a bit.