The dialect situation--that is, what is properly a variant of Standard Thai or a separate language--has not been settled. Some list only Khorat Thai as a dialect. Other distinctions are made between the dialect of Bangkok and that of Central Thai itself.

Others group Northern Thai (Lanna), Northeastern Thai (Isan), and Southern Thai as variants or regional dialects of Standard Thai. Others are ambiguous about the question. Still other authorities list these as separate but closely related languages. A terminological problem also exists: Isan, which is closely related to Lao and spoken in northeastern Thailand, is also called Northeastern Thai; Lanna which is spoken by the Khon Muang people in the northern provinces of Thailand is also called Northern Thai; Lao, which is spoken in Laos is also called Eastern Thai.