Spelling variants and varieties include the following (Sidwell 2005:11).
Souei. The term "Souei" is also applied to other groups, such as a Pearic community in Cambodia.
Suai. The Kui are known among the Lao and Isan people as the /sùai/, which is an annual tribute or tax (such as forest products) that the Kui had to send to Bangkok every year.
Van der haak & Woykos (1987-1988) identified two major Kui varieties in Surin and Sisaket provinces of eastern Thailand, Kuuy and Kuay. Van der haak & Woykos also identified the following divergent Kui varieties in Sisaket Province, Thailand.