According to the objective approved by the Council of the European Union, a climate neutral European Union must be achieved by 2050. This means that in the period up to 2050, the European Union must significantly reduce greenhouse gas emissions and find ways to offset the remaining and unavoidable emissions. According to the policy makers of the European Union, the introduction of the concept of energy communities is a way to restructure the energy system, thus allowing citizens to actively participate in the energy transition and thus as energy users in residential buildings enjoy greater benefits. When getting acquainted with the scientific literature on energy communities, there was a great uncertainty about the concept of energy communities and different understanding of it by different authors. Therefore, the study of the energy community concept is problematic due to several aspects. Firstly, different terms are used in the scientific literature to denote the same concept. For example, the term “energy community”, “energy cooperative”, “community energy project” can mean the same citizen initiative in the field of energy. Secondly, the term “energy community” can also be understood as conceptually completely different concepts in different studies. Moreover it follows from the Directive (EU) 2019/944 of the European Parliament and of the Council on common rules for the internal electricity market and which amends Directive 2012/27/EU Recital 43, that in accordance with this directive, only pre-existing resident electricity initiatives as determined categories are recognized as “residential energy communities” at the Union level. Therefore, it is essential to clarify the conceptual difference between energy communities, mutual trade and collective self-consumption, based on both the analysis of the European Union directives and the scientific publications that discuss the concept of energy communities in relation to the above mentioned directives.