The article elaborates the conceptual difference between two core concepts of the French approach of economics of convention (EC), namely convention and institution. It is argued that modern institutionalisms and neo-institutionalisms need to delimit the meaning of the notion institution as EC does. Then it is possible to work out the relations of institutions and other forms of cultural or structural resources. A proposal for such an elaboration is done by differing four perceived situations for institutional analysis. This elaboration could be used to enhance the explanatory capabilities of EC.