what's the difference between a proclamation and a declaration
Proclamation A proclamation (Lat. proclamare, to make public by announcement) is an official declaration issued by a person of authority to make certain announcements known. Proclamations are currently used within the governing framework of some nations and are usually issued in the name of the head of state.
Declaration of war The legality of who is competent to declare war varies between nations and forms of government. In many nations, that power is given to the head of state or sovereign. In other cases, something short of a full declaration of war, such as a letter of marque or a covert operation, may authorise war-like acts by privateers or mercenaries. The official international protocol for declaring war was defined in the Hague Convention (III) of 1907 on the Opening of Hostilities.