agreement, contract, treaty, convention, bargain, understanding, accord
These words have one thing in common, that is, they all mean “协议” to different extent. The subtle difference is going to be clarified here.
agreement : An arrangement between parties regarding a method of action; a covenant.
contract ：An agreement between two or more parties, especially one that is written and enforceable by law.
treaty ：A formal agreement between two or more states, as in reference to terms of peace or trade.
convention ：An agreement between states, sides, or military forces, especially an international agreement dealing with a specific subject, such as the treatment of prisoners of war.
bargain ：An agreement establishing the terms of a sale or exchange of goods or services.
understanding ：A compact implicit between two or more people or groups.
accord ：A settlement of points at issue between nations.