What is the true difference between intellectuals and intelligentsia?

There is no such term as the intelligentsia, except Russia, generalizing all representatives of intellectual labor. In the rest of the world, the cultural layer of the nation is called intellectuals, and the term intelligentsia is not applied.However, in reality, representatives of intellectual labor in any country in the world are divided into four groups, indicated below, among which there is also the intelligentsia. Therefore, it makes sense to demonstrate with the example of Russia what properties one of these groups (the intelligentsia) possesses, who can be attributed to it, and what its role in public life is.