[khaleej]

After having an ESL student in my class last year, I have decided to take an ESL course. However, I am confused by TESOL, TEFL, TESL and CELTA. I would prefer to teach ESL to children and not adults (both in Canada and abroad). I have a diploma in Montessori (6-9). I don't mind starting low and work towards a degree in ESL if such exists. (I have a degree, just not in Education and unfortunately Montessori just have diplomas of different age groups).

English is my first language. My degree is not Canada based but my Montessori diploma is; if this info helps.

What route should I take? Any lead given will be highly appreciated.

[broomrider]

There is an international professional organization TESOL (Teachers of English to Speakers of Other Languages) which may be of help. You might write them asking for guidance about courses and certification in Canada.
https://www.tesol.org

If you have a college or university in commuting distance, you might contact them for information about their course offerings in your area of interest. If they don't have a program, someone there in the education department may be able to direct you to an institution that does.

This site might be of help, I'm not familiar with them and always suggest checking unknowns out carefully before investing. They have some interesting looking links, at any rate.
http://www.americantesol.com/tesol-certification.html

I like the site http://www.colorincolorado.org which has information mainly for parents and teachers, but gives some good information on various topics.

I hope you find something useful in the above. Good teachers are always needed for those learning the language while learning academics.

I am not sure I totally understand your question. If you want to teach ESL to children in a school in Canada you need to be a qualified teacher with an ESL qualification. If you want to teach in a private or after school setting you may be able to use an international ESL certification.