Although having similar English equivalents, social constructionism and epistemological constructivism are different schools of thought; the first one is an effective theory in epistemology, and the other one is a sociological theory about cognition. The first part of the article introduces the main concepts of each school of thought and their formulation, and then the roles of dominant thoughts for each of them, the analysis of other subject topics such as educational theories, social discrimination, the concept of refugee and even the philosophy of science and the importance of the book “the Reality of Constructionism” are discussed. At the end, these theories are examined from different points of views and the weak points and strong points of each of them are discussed.