Some theoretical and practical aspects of integration relations in regional groupings has not been studied and require further analysis. Economists and other practitioners stress that there has not been developed yet a unified theory of integration covering various aspects of this process. Analysis of domestic and foreign scientific literature shows that currently there is no clear definition of the «differentiated economic integration» concept, which is a system of alternative theories of international economic integration.In this study the emphasis is placed: firstly special attention is paid to economic integration, not political. Initially, differentiated integration was positioned as multi-level governance in the field of decision-maki...