An ambassodor works in an Embassy. A consul works in a Consulate.
An ambassador is an important official who lives in a foreign country to represent his or her own country there. The ambassador is based in the capital city of that country. For example, the British Ambassador reprsents Britain at the British Embassy in Beijing.
A consul is an official chosen by a government to live in a foreign city to take care of people and businesses from the consul's own country. A British Consul works in the British Consulate in Admiralty, Hong Kong. Another British Consul works in the British Consulate in Guanghzhou.