English as a Foreign Language (EFL) is teaching English in a country or region where English is not spoken outside the class. English as Second Language (ESL) is when non-native English speakers are taught English in a country or region where English is spoken outside the class.
A seemingly simple distinction, the two are different.
The most important point though, from our point of view as an educator, is that with EFL, once we leave work, we need to speak a foreign language, whereas, with ESL, once we leave work, we can relax in an English speaking environment. An interesting choice…