What's the difference between "dictator", "tyrant" and "despot" (in terms of a ruler)?

Solution 1:

  1. No. See below.
  2. Yes, usually.

While all terms refer to absolute authority, and in this day where democracy is widely accepted all have negative connotations, these functions have a long history and started out being perfectly respectable.

Dictator originated as a Roman function of absolute authority for a short period in times of war. It simply means "one who gives orders". Sulla was one of the first persons to abuse these powers.

Tyrant originates from Greek tradition and refers to anyone, good or bad, who obtains executive power in a polis by unconventional means. Athens gave the title of tyrant to Peisistratus in 546 BC and prospered.

In its classical form, despotism is a state in which a single individual (the despot) holds all the power and authority embodying the state, and everyone else is a subsidiary person. It was a common form of early statehood and civilization, a well-known example is the Pharaoh of Egypt.

Fear of abuse made the principle of absolute rule controversial from ancient times onwards.

Enlightened absolutism (also known as benevolent despotism), came to prominence in 18th century Europe where absolute monarchs used their authority to institute a number of reforms in the political systems and societies of their countries.
This movement was quite probably triggered by the ideas of the Age of Enlightenment. But it never really took hold in a world on the way to more representative forms of government.

These days absolute rule irrevocably holds a negative meaning. In actual fact someone like Niccolò Machiavelli would rejoice.

References:
https://en.wikipedia.org/wiki/Tyrant
https://en.wikipedia.org/wiki/Dictator
https://en.wikipedia.org/wiki/Despotism
https://en.wikipedia.org/wiki/Niccolò_Machiavelli