The article presents the results of a comparative analysis of ethno-political transformation in the Republic of Belarus and in the Republic of Ukraine in the post-Soviet period. Thanks to the comparative statistical and substantial analysis of the migratory behavior in each of the two cases, the author has determined the differentiation between the two models of ethnical development. Impartial analysis shows that the Belarus model is aimed at construction of the political nation providing civil consensus of all ethnic groups. The Ukrainian model actually pursues construction of the ethno-cultural nation based on cultural-political isolation of ethnic groups, which creates preconditions for interethnic conflicts.