These are the teachers who have taken the time and effort to get qualified in their own country. In the UK this is normally a degree (not necessarily in education) and a PGCE (post graduate in Education). To make yourself as employable as possible Qualified Teacher Status (QTS) is necessary.
Once you have this you will find it easy to get work nearly anywhere in the world, with a much higher salary than unqualified teachers. In China a qualified teacher can expect to earn more than 25k RMB, with bonuses, living allowances and flights in addition.
Transitional TEFL Teacher
These are the teachers who normally studied something else at university and later in life decided to teach. They may or may not have had a degree but are prepared to invest in their education, with the aim of a well paid position in an international school but perhaps reluctant to go home and study. Usually they start of with just a TEFL or CELTA and work at a bilingual/ government school or a language center.
They may have started off low down in the teaching market but are determined to make a career out of teaching. For people who fall into this category unless they are willing to go home and study, I would recommend the PGCEi.
Teachers here may be more willing to work in less glamorous locations as they prioritise jobs and opportunities. By the very nature of a transitional teacher, they are unlikely to stay in the same job long, and are always looking to improve their salaries by moving often. A teacher in this position would probably start off around 10k RMB a month and after a few years be earning more than 20k RMB, hopefully earning a good position in an international school.
The TEFL teacher is a teacher with a TEFL or CELTA. Usually they have done at least a month long course and have a degree. A TEFL teacher is happy with where they are, whilst possible hoping to work at an international school (it is possible) without doing any further education. In China there is massive market for teachers and a TEFL and degree is more than enough for the majority of teaching positions.
Usually they will work in government/ bilingual schools or language centers, where wages are usually around 10-20k RMB.
These teachers are usually looking to teach for a short time as they want to experience a year working away from home. They are less motivated to do expensive and time consuming courses are on-line TEFL's are a particular favourite. Salaries for these teachers are similar to TEFL teachers as the jobs are the same, but as they lack experience they are more likely to be earning around 10,000RMB