Differences between OIE and NIE:

The differences between OIE and NIE may, therefore, be dichotomized into the following:

• non-formalism versus formalism;
• holism versus individualism;
• behaviorism (i.e. unconscious or sub-rational) versus rational choice;
• evolutionary (i.e. invisible hand orders) versus collectivism (designed orders);
• interventionist (distribution of income and regulation) versus non- interventionist; and
• induction versus deduction.

In the above dichotomization, the term formalism has a specific connotation in that it refers to the usage of mathematical modeling in economics. While the NIE adopts models (representing a set of assumptions, equations, estimation of parameters, testing, simulation, etc.) very commonly, the OIE's style of presenting theories is considered informal Ad rhetorical. However, it is said that the impression of the OIE as anti-theoretical or purely descriptive is not altogether correct as the work of Mitchell and Commons contain theoretical/formal underpinnings. But since many old institutionalizes resisted (or avoided being formal), the trend gave the false impression that OIE lacked theoretical support. Acknowledging that the neoclassical economics was most formal than others, it is held that 'NIE is less formal than neoclassical economics but somewhat more formal than OIE'. In this context, there is an assertion that both the OIE and the NIE need more formalist and non- formalist methods to advance their own fields of institutional theories.