Royalty, ecclesiastics and lay people use different pronouns and different qualifying nouns and verbs.

Thai Language Regional variation
There are four major dialects within Thailand, corresponding to the southern, northern ("Yuan"), northeastern (close to Lao language), and central regions of the country. The central region dialect is called Central Thai or Bangkok Thai is widely understood in all the regions and taught in all schools and used by most television broadcasts.
Different class of the Thai language
Different class - royalty, ecclesiastics and lay people use different pronouns (at least 47, including some 17 I's and 19 you's) and different qualifying nouns and verbs.
Because Thai's pronominal structure illustrates rank and intimacy, there are, in effect, different languages: (i) Street Thai (spoken Thai) which is informal as used between friends and close relatives, without polite terms of address; (ii) Elegant Thai (written Thai) which is the official and written version and includes respectful terms of address; (iii) Rhetorical Thai which is used for public speaking, (iv) Religious Thai (heavily influenced by Sanskrit and Pli) which is used when Buddhism is discussed or in addressing monks; and (v) Royal Thai (influenced by Khmer) which is used when addressing members of the royal family or describing their activities. Most Thais can speak up to the first and second levels, but they will understand the others.
There are also few minor Thai dialects like Lue and Phuan that are spoken by small populations. Also within Thailand are the so-called ghill tribesh, and some other small ethnic minority groups that account for around 60 languages not considered related to Thai.
And yes, English is now taught in all public schools.