I think the word system means a specific entity with stable interactions between its units. As for the word regime, it means that there is an entity that has interactions within its units and works for a specific purpose that it has not yet reached. Therefore, it is a temporary entity that ends with the end of achieving its goal, such as trying to lose weight, for example

A political regime is a set of political structures that make up a state. A political regime may also be known as a form of government, a state system, or a political system. The term political regime may also sometimes refer to a specific ruler or set of rulers within a political system. There are many different types of political regimes in the modern world, and many more have existed historically. These range from the directly-democratic political regime of Anarchism to totalitarian regimes such as Military Dictatorships or Fascism. The political system that Americans are most familiar with is Representative Democracy. This is a political system in which representatives are directly elected by the citizenry, and these representatives then make political decisions for the populace, with the assumption that their decisions will reflect the general will of the Republic. This can be compared to a Direct Democracy, in which the citizenry directly votes on all issues of importance.

The true meaning of 'regime' is really 'a form or system of control or government'. It is frequently used to describe a government headed by a specific person (the Saddam regime) or based on a particular ideology ( a fascist regime). Some people use the term to describe governments which they consider to be repressive or undemocratic and so give it a negative sense but in reality 'regime' is a neutral term. Political system is a complicated term which has several meanings but in short... A political system is the way in which a country is governed, how government is organized and how the government makes policies. Democracy/ Communism/ Monarchy are all political systems.

In Algeria, regime. In the free world, system. Regime = controls the courts System = is controlled by the courts