[MeteorMarc]

The title contains hierarchical, which does not come back in the post. You probably need hierarchy, otherwise state charts become unweildingly large.

[embedding-shape]

A statechart without hierarchy is just a state machine. It's the composition and hierarchy that turns a state machine into a statechart.

[knollimar]

Is the very first example not one without hierarchy and thus just a state machine?

[embedding-shape]

Technically yes, that's just a state machine. On https://statecharts.dev/what-is-a-state-machine.html the website itself also admits that that example is a "simple state machine", and on https://statecharts.dev/what-is-a-statechart.html you get the better explanation with

> A statechart is a state machine where each state in the state machine may define its own subordinate state machines, called substates

[codethief]

It does if you click on "What is a statechart?", https://statecharts.dev/what-is-a-statechart.html .

> The primary feature of statecharts is that states can be organized in a hierarchy: A statechart is a state machine where each state in the state machine may define its own subordinate state machines, called substates. Those states can again define substates.