Answer:
Definition. A treaty is a formally concluded, ratified and binding agreement between sovereign states and/or international organizations while an executive agreement is an agreement between the government heads.
Nature. Another major difference between treaty and executive agreement is that treaties are legally binding between two states while executive agreements are politically binding between the heads of two states.
Purpose. The purpose of a treaty varies in all dimensions under international relations such as peace, trade, independence, reparations, territorial boundaries, human rights, immigration, etc. between the parties concerned.