Although belonging to the same ethnic group, some aspects of the culture of every sub-ethnic group are specific. As expressed through a comparative study of the Thai culture in Thanh Hoa province and the Thai culture in Northwestern Vietnam. The study examines Thai livelihoods, social structure and some aspects of physical culture (such as houses, costumes), and spiritual culture (wedding and funeral ceremonies). It is found that the typical characteristics of the Thai sub-ethnic group in various areas reflect differences in the natural and socio-economic conditions. This study shows it is important to pay attention to the particular characteristics of culture in every region.