A Diplomatic Mission is the office of a country's diplomatic representatives in the capital city of another country.
Diplomatic Missions are established in accordance with the provisions of the Vienna Convention on Diplomatic Relations 1961.
A Diplomatic Mission of a Commonwealth country in another Commonwealth country is called a 'High Commission'. The head of mission is called 'High Commissioner'.
A Diplomatic Mission in any foreign (ie non-Commonwealth) country is called an 'Embassy' and the head of mission is called 'Ambassador'.
High Commissions and Embassies perform the same functions and have the same status.
A Consular Mission is the office of a country's consular representative in another country, either in the capital city or in another significant city. Consular representatives undertake a more restricted range of duties than diplomatic representatives. Their prime task is to protect the interests of the nationals of their countries.
Consular Missions are established in accordance with the provisions of the Vienna Convention on Consular Relations 1963.
The Convention provides four different grades of Consular representatives (in descending order of importance): Consul-General, Consul, Vice-Consul, and Consular Agent. The offices of these representatives are called Consulate-General, Consulate, Vice-Consulate and Consular Agency, respectively.
Consular representatives may be career officers (ie they are full time employees of their government) or honorary officers (ie officers paid only an honorarium by the country they represent). Career officers are normally nationals of the country they represent and members of that country's diplomatic or consular service. Honorary officers are usually permanent residents of the country in which they work and may be nationals of the country in which they live or of the country that they represent. Honorary Consulates do not provide the same services as a Diplomatic Mission.
In some Commonwealth countries, the senior consular missions of other Commonwealth countries are called Deputy High Commissions and the heads of these offices are called Deputy High Commissioners. However, the trend is for such offices to be called Consulate-General etc.