The Republic of Belarus is the only state of the Near Abroad, where, with a reduction in the share of the Russian population, since the beginning of the 21st century, there has been an increase in the proportion of citizens who called Russian their native language and actively used it in everyday life. Ukraine, despite the signifcant similarity with the Republic of Belarus in the linguistic structure of the population, is the direct opposite of the latter in the course of linguistic processes. The purpose of the article is to compare the course of ethnolinguistic processes in these two neighboring countries. The study assesses the change in the size of the main ethnic communities and linguistic groups of Ukraine in the period from 2001 to 2021, depending on the scenario of ethnolinguistic dynamics — actually “Ukrainian” and “Belarusian”. The study revealed that in the population of Ukraine the main shifts took place within the groups of bilinguals (or biethnophores) that changed their identity depending on the political situation. Despite Ukraine’s notable successes in “titulating” and linguistic assimilation of the non-Ukrainian population, in the transition to the “Belarusian” version of the national policy, due to the high proportion of bilinguals in the population, these processes can reverse.