An ESL classroom
is in a country where English is the dominant language. The students are immigrants or visitors. The class is usually of mixed nationalities, so students don’t share a native language or a common culture. Outside the classroom, students have a specific, practical need for English, and ample opportunity to use it.
An ESL classroom is far more likely to have students from many different countries, all with different native languages, whereas an EFL classroom isn’t. In this instance, the teacher needs to be prepared for different cultures and different linguistic mistakes along the way.