After the fall of the Khmer Rouge, how did the government of Cambodia change?

After the fall of Khmer Rouge Cambodia was invaded by Vietnamese forces, in opposition to that the Coalition Government of Democratic Kampuchea - CGDK was created from three factions - Khmer Rouge, Sihanouk, and Khmer People's National Liberation Front. Peace was achieved by UN - United Nations Transitional Authority in Cambodia.

Later in 1993, there was a restoration of the monarchy, but it lasted a few years until co-Prime Minister Hun Sen did a coup d'état.

A few years later Cambodia found stability with a multiparty democracy under a constitutional monarchy.

The Khmer Rouge fell in 1979, when the Cambodian capital, Pnom Penh, was taken by the Vietnamese armies. This meant the dissolution of Pol Pot's regime known as Democratic Kampuchea, which was allied to China, and the establishment of a new regime called People's Republic of Kampuchea, allied to the Soviet Union. The new regime was welcomed by most of Cambodians that suffered the Khmer Rouge's brutality, and its main goals were to restore the economy and to fight the Khmer Rouge groups, which were hiding in the North-West region of the country and started a guerrilla war against the new government. It continued as a communist state, but under the orbit of the Soviet Union instead of China, and abandoned the Khmer Rouge's extremist and intolerant policies. It focused on building a socialist economy in a more pragmatical way and became more welcoming towards different ethnic minorities and religions that were persecuted under Pol Pot's government.