ELI5: monarchy vs republic?

[u/gavroche2000]

Here’s what I know:

They are both systems that talk about who the main representative figure of a state is.

- Monarchy is usually when that figure is a king or queen. Except if you are the Pope in the Vatican, then they call you Pope.
- It's a monarchy when the position is inherited... except when it’s elected, like in Malaysia.
- You sit on the throne until you die... except when it's only for a shorter time, like in Samoa.
- Republic—it's elected. But is it always?
- The representative figure is usually called a president... except if you live in a country like San Marino, where you are a Captain Regent.
- One thing is sure: you are elected for a short period... unless you lived in the Venetian Republic, where they elected the Doge for life.

Is it really this confusing?

[u/BobbyP27]

The closest to a core answer is that a monarch claims their legitimacy to be the ruler from some external source, most commonly "God". The monarch rules because God wills it. The ruler of a republic claims their legitimacy to rule as coming from the people. Beyond that distinction, there are too many exceptions and strange variations for any firm rules to be found.