The core idea behind these two forms of government is the concentration of power. In Autocracies, power is concentrated in the hands of a single individual, while in Authoritarianism, it resides with a small group known as elites.
Power concentration occurs even in democratic and socialist organizations, a concept known as the Iron Law of Oligarchy. This appears to be a natural force in human societies, similar to gravity.
So, why do we even have democracies? How do they come into existence? I will try to answer that in tomorrow's post.
I'd like to highlight the big role of palace intrigue in autocracies. Sometimes I can tell Western political scientists haven't studied the other system much, and in their works are under the impression what the dictator says just goes, which is an oversimplification.
In reality, nobody defies the king to his face, but lieutenants will absolutely reinterpret, bend, quietly ignore or even fabricate the execution of orders to their advantage. Corruption is universal in non-democratic systems for this reason, and in some cases becomes difficult to distinguish from legitimate government workings.