Grand Theory- is a term that was originated from the American sociologist C.Wright Mills in The Sociological Imagination to talk about the form of highly abstract theorizing in which the formal organization and arrangement of concepts of human takes priority over understanding the social environment/world. According to Mills, this theory was more or less separated from the concrete concerns of daily life and its variety in terms of time and space.Mills was trying to prove to Talcott Parsons ( Architect of structural functionalism and American sociologist) who is against in it and insisted that here is no Grand Theory in the sense of one universal scheme to fully understand the unity of social structures.
Middle Range Theory-this theory was developed by Robert K. Merton( sociological theorizing aimed at integrating theory and research about empirical). It is currently the de facto dominant approach to sociological theory construction,especially in the country of the the United States. In addition to Middle Range Theory, it is a term that does not refer to a specific theory, but rather it is an approach on theory construction.