The analyses of publications show unclear differences between the definition of a digital city and a smart city. The critical analysis of references allows us to define the role of a digital dimension of a smart city. A deeper analysis of the concept of smart social systems shows that many social systems can be smart without necessarily basing their activities on Information and investigated taking into account its relationship with the environment. The paper considers the importance of a digital platform for the smart social systems of the city. Theoretical considerations have been used to develop a conceptual model for evaluation of the importance of a digital dimension for a smart city.