What do EFL and ESL stand for?...

The former refers to English as a second language, when students have a low proficiency level of the language.

The latter refers to English as a foreign language, as it happens when the teacher is a native speaker and is fluent in the students' language.

The latter refers to English being taught and learned as a second language, what happens when immigrants learn the language in the countries they are living in.

The former refers to English being taught for specific purposes, according to students' particular needs.

The latter refers to English being taught and learned as it happens in regular schools in Brazil and in any country where English is not the official language.