Nowadays, the concepts of efficiency and effectiveness are gaining importance in business and beyond. This is due to the decline in the regenerative capacity of natural resources, climate change caused by environmental pollution, and the need to maintain the competitiveness of social systems as economic globalisation intensifies. The research results reveal that the pluralism of interpretation and extrapolation of these concepts is beginning to border on scientifically incorrect attitudes towards their interpretation and application in research and practice. Moreover, in many scientific sources, efficiency and effectiveness are interpreted differently and/or in a way that is inconsistent with the nature of effectiveness. This creates a fertile ground for pseudo-scientific knowledge in the academic information space and reduces the scope for applying these concepts in practice in the context of maintaining the competitiveness of an enterprise or other organisation in a constantly changing business environment. This situation is largely due to the lack of a general form and general mathematical models of the concepts. Therefore, this study critically analyses the content of the concepts “efficiency” and “effectiveness” and identifies the elements that make up their content in order to use them for the development of general mathematical models. The research results are of great importance for the evaluation of business performance and for management decision-making in order to improve the competitiveness of enterprises. In addition, general mathematical models of the concepts “efficiency” and “effectiveness” can be applied to the analysis of the performance of other organisations, creating a favourable ground for the achievement of goals under conditions of limited resources, as well as for limiting the intensity of the decline in the regenerative capacity of natural resources.