The distinctions are mainly related to their method of authorisation. Contracts must be advised and approved by two-thirds of the senators present, but executive agreements alone can be executed by the President. Some contracts give the president the power to fill gaps through executive agreements rather than additional contracts or protocols. Finally, agreements between Congress and the executive branch require the approval of the House of Representatives and the Senate before or after the president signs the treaty. A treaty is a formal and binding written agreement that is concluded by actors in international law, usually sovereign states and international organizations, but may involve individuals and other actors.  A treaty can also be described as an international agreement, protocol, treaty, convention, pact or exchange of letters. Regardless of terminology, only instruments that are binding on the parties are considered treaties of international law.  A treaty is binding under international law. The language of treaties, such as that of a law or contract, must be interpreted if the text does not appear clear or if it is not immediately clear how it should be applied in a perhaps unforeseen circumstance. The Vienna Convention stipulates that treaties must be interpreted in “good faith” according to “the ordinary meaning given to the contractual terms in context and in light of their purpose and purpose.” International legal experts also often invoke the “principle of the greatest possible effectiveness,” which interprets the language of the treaty so that it has the maximum strength and effectiveness in defining obligations between the parties. In the United States, the term “treaty” has a different, more limited legal meaning than in international law.
U.S. legislation distinguishes what it calls “treaties” from “executive agreements” that are either “executive agreements of Congress” or “single executive agreements.” Classes are all treatises of international law in the same way; they differ only in U.S. domestic law. The separation between the two is often unclear and is often politicized in disagreements within a government over a treaty, because a treaty cannot be implemented without a proper change in national legislation. When a treaty requires laws of application, a state may be late in its obligations if its legislator does not pass the necessary national laws.