This stands for Teaching English as a Foreign Language. The term term is usually used when English teachers work abroad in a country where English isn't the first language. For example you could be teaching English in China to Chinese people, this is an example of being a TEFL teacher.
This term means 'Teaching English as a Second Language.' This means when a teacher leads English lessons in a country where English is the first language. For example you could be teaching English in The UK, Australia or USA giving lessons to non-native speakers of English who are looking to improve their language skills.
This is a popular term which you will hear a lot and stands for 'Teaching English to Speakers of Other Languages.' Basically TESOL means teaching English abroad to all people, it includes both the terms described above.
This means 'English Language Teaching.' and you will probably hear this in the UK by language schools and other TEFL institutions.
This term means 'English as a second language.'
If you need any help with any terms about teaching English abroad please get in touch with us.