This article shows the similarities and dissimilarities of architecture of Thai houses in different regions and among different Thai sub-ethnic goups. The similarities of Thai architecture originates &om a fact that both the Thai sub-ethnic groups in Thanh Hoa province and in the Northwest Vietnam belong to the same Thai culture. The different features of the traditonal architecture of Thai homes reflect differnces in local and regional. The Northwest region is considered a center of the Thai culture in Vietnam, while the mountainous areas of Thanh Hoa and Nghe An provinces are in the margins of the cultural center. These areas are influenced by many factors such as historical circumstances, cultural exchanges of nearby ethnic groups, and internal regional factors.