The DELTA is the Diploma of English Language Teaching To Adults; according to the DELTA website, it can be done full-time over two to three months or part-time over six months to a year. Distance courses are also possible in addition to the standard in-person variety. A piece of advice I’ve heard more than once is: get a headstart on the reading.
To apply at any of the 55 centres in 20 countries offering the DELTA, you should have at least two years experience (in the last five years) teaching English to adults, in different contexts and at different levels. You should also “be a graduate and/or have an initial teaching qualification” and have a level of English which allows you to teach different levels. Sometimes the DELTA is integrated into MA programs, menaing that a successfully completed DELTA can get you an exemption from a portion of the MA requirements.
I certainly don’t have a DELTA or MA myself, so I am hardly the person to be explaining the difference between these programs in detail – and as it seems few people have both, very few are in a position to actually compare them first hand. I’ve summarized the DELTA in this post not because I necessarily think it’s a better program, but because it’s one program; there are tons upon tons of MA programs, which, in my view, means that there is not one that I can post on that will be “equivalent” to a post on the DELTA.
I question the motives of teachers who go to extremes to say one program is without a doubt better than the other – these are definitely different programs and which one is better for you will depend on your experience, current situation/location, and career goals. Often a DELTA or an MA is required for DOS (Director of Studies) and teacher trainer positions.