I'm studying Thai up here in Chiang Mai, and even in our Thai class, we get words that are sometimes spelled one way, and the next day, spelled another way! A bit confusing, to say the least.
And just being out and about, I've come across 2 different signs with what seemed like 2 different words. On closer inspection, however, the 2 words turn out to be the SAME word, with quite different spellings.
Then again, I used to teach English, and I honestly believe that English is more confusing than Thai.