【Ambassador】 , 【Legate】 , 【Nuncio】 , 【Minister】 , 【Envoy】 , 【Internuncio】 and Chargé d’affaires all designate a diplomatic agent serving his sovereign or government in a foreign country and are here compared with reference to their order of precedence as fixed by international regulations and protocol.

【Ambassador】 , 【legate】 , and 【nuncio】 designate a diplomatic agent of the first rank who is accredited to the head of the state in which he serves, is considered to represent both the government and the person of the head of state whom he serves, and as the personal representative of his sovereign or chief executive enjoys certain privileges and precedences not shared by diplomats of lesser rank.

An 【ambassador】 (in full 【ambassador】 extraordinary and plenipotentiary) is almost always a resident agent, though the term may also denote one who goes on a special mission as the chief executive’s diplomatic agent. In this case he may be distinguished as an 【ambassador】 -at-large.

The comparable diplomatic agents of the pope are called 【legate】 and 【nuncio】 , the difference between them being that a 【legate】 goes on a special mission and is clothed with authority to act in the name of the pope and a 【nuncio】 serves as the accredited resident 【ambassador】 of the Holy See at a foreign court or seat of government.

【Minister】 designates a diplomatic agent of the second or of the third rank. He, too, is accredited to the head of the state to which he is sent but as the representative solely of the government and not of the person of the head of his own state. As an agent of the second rank, he may also be called an 【envoy】 , for his full title is 【envoy】 extraordinary and 【minister】 plenipotentiary.

【Internuncio】 is the designation of the papal diplomatic agent of the second rank equivalent to an 【envoy】 extraordinary and 【minister】 plenipotentiary. Agents of the third rank, called more fully ministers resident are now uncommon. They perform essentially the same function as the 【envoy】 extraordinary and 【minister】 plenipotentiary but are usually assigned to less important capitals.

A chargé d’affaires is an agent of the fourth rank who directs diplomatic affairs in place of an 【ambassador】 or 【minister】 in the absence or lack of such higher-ranked agent. He is accredited to the head of the department dealing with foreign affairs rather than to the head of the state and his appointment may be on a permanent footing and by his home government or on an interim basis by the head of a mission (an 【ambassador】 or 【minister】 ).