Executive orders are issued from the executive branch of the government, specifically the U.S. President or the state governor. An executive does not go through the legislative process, but it has the force of law. It is not binding on everyone, only on employees of the executive branch. However, executive orders are subject to judicial review after the fact (i.e. they can be declared unconstitutional by the court).
Presidential memoranda and proclamations are statements of policy and direct the actions, procedures, and policies of the executive departments and agencies.