asiaexpat,
ESL: English as a Second Language
Which means the study or learning of English in an environment where English is the predominant language, by someone whose first language is not English.
EFL: English as a Foreign Language
The study or learning of English in an environment where English is not already the predominant language, such as in a non English speaking country, by someone whose first language is not English.
You often find these words used interchangably
TEFL: Teaching English as a Foreign Language
Teaching English as a Foreign Language – is an industry catering for students studying English in non-English speaking countries (see EFL). It is often taught by both native English speakers and local experts, although native English speakers are generally considered preferable. Common qualifications for TEFL teachers include certificates and diplomas issued by UCLES (University of Cambridge Local Examinations Syndicate) and Trinity International Examinations Board of Trinity College, London.
To learn more see this thread:
http://eslhq.com/forums/showthread.p...o=newpost&t=68