Supranationalism is the existence of authority which is higher than that of
nation-state. After nation-states have consented to becoming a part of the
supranational body, it has the capability of imposing its will on its constituent
nation states, for example, one way is through laws that, if passed through the
supranational legislature, are binding on the constituent nation-states. Under
this, sovereignity and decision-making authority is transferred from the
constituent bodies to the international or regional organisation.
Intergovernmentalism refers to the interaction amongst nation-states which
takes place on the basis of sovereign independence.In such bodies, state
sovereignity is preserved through the process of unanimous decision making
where each entity has a veto.