I have read that certain areas of Thailand produce certain styles of Muay Thai.
Unfortunately, I couldn't find any detailed information, but from what I could gather, it seemed that in a particular region of the country more emphasis will be put on a certain aspect of the fight ( for example: clinch), while in another a fighter will use a particular guard. It would be interesting to try and draw a map of the different fighting styles according to the different areas of the country.
I don't think this has to do with the actual style of the single fighter (Muay Khao, Muay Mat, etc.): it rather seems to be something more "at the source", it seems to have to do with how every part of Thailand developed its own branch of Muay Thai.
Does it make sense?