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. An agreement covers any form of agreement, negotiated solution or agreement between two or more parties. This is a legally enforceable agreement between two or more legally competent parties. Under international law, a treaty is a legally binding agreement between states (countries). A treaty can be called a convention, protocol, pact, agreement, etc. It is the content of the agreement, not its name, that makes it a treaty. Thus, the Geneva Protocol and the Biological Weapons Convention are the two treaties, although neither treaty in its name. Under U.S. law, a treaty is a legally binding agreement between countries that requires ratification and “consultation and approval” of the Senate. All other agreements (internationally treated) are called executive agreements, but are nevertheless legally binding on the United States under international law. Before 1871, the U.S. government regularly entered into contracts with Indians, but the Indians Appropriation Act of March 3, 1871 (Chapter 120, 16 Stat.
563) had a horseman (25 US. C No. 71), which effectively ended the drafting of presidential treaties by declaring that no Indian nation or Indian tribe can be recognized as a nation, tribe or independent power with which the United States can enter into contractual contracts. After 1871, the federal government continued to maintain similar contractual relations with Indian tribes through agreements, statutes and executive ordinances.  Contracts sometimes contain self-performance clauses, which means that the contract is automatically terminated if certain defined conditions are met. Some contracts should only be binding temporarily by the parties and will expire at some point. Other contracts may be terminated themselves if the contract is to be concluded only under certain conditions.  Another situation may occur when one party wishes to create an obligation of international law, but not the other party. This factor has been at work in the run-up to talks between North Korea and the United States on security guarantees and the proliferation of nuclear weapons. Agreements are binding only if the parties intend to form legal ties. An agreement between the parties also means a meeting of minds, an agreement of opinion and determination of the parties, parties who have come together to express a common and common goal. The writing or instrument of such a negotiated solution is proof of an agreement.
Agreements have different forms and transcend national borders. There are different types of agreements, including conditional agreements, contracts, trade agreements, explicit agreements in which terms and conditions are explicitly stated and invoked by the parties at the time of the agreement and treated. An essential part of treaty drafting is that the signing of a treaty implies recognition, that the other party is a sovereign state and that the agreement, considered to be under international law, is applicable. Therefore, nations can be very cautious when it comes to qualifying a treaty agreement.