Special administrative region

Special administrative regions (SARs) are regions within Mainland China that have their own governments separate from the rest of China. As a result of this, they enjoy a high degree of freedom. The two SARs are Hong Kong and Macau, both were European colonies that got transferred to China during the 1990s.
Due to their new addition to the territory of China, Article 31 of the Chinese Constitution forms the legal foundation for the territories, as opposed to Article 30 which establishes the rest of China's territory.
Government System.
The term used to refer to the government of Hong Kong and Macau is the phrase, "One country, two systems", coined by Deng Xiaoping in which the territories would be part of one country (China) but use two different systems of government (Hong Kong and Macau basic law) instead of the Communist system of the Chinese national government. This was done to prevent protest of the new government and a loss of freedom that citizens may attribute it to.