Elections aren't rigged but everything else is rigged, like media is controlled by government or opposition candidates are jailed.

In Russia the elections actually are rigged and China doesn't have elections so they are both dictatorships.

Granted the line between them is fuzzy so it's more helpful to think of it as a spectrum.

I refer to what political scientists write about the subject.

Illiberal democracy (aka electoral authoritarianism, competitive authoritarianism, or soft authoritarianism) is a system with democratic institutions that don't work properly. Opposition can still win but it's not a fair game.

>And if there is a significant difference, what stops one becoming the other?

People. For example, Ukraine was illiberal democracy and Orange Revolution 2004 changed that. Poland was slipping badly but 2023 Polish protests changed things.

Putin started with illiberal democracy and slipped into pure authoritarian eventually, because Russians can't get their shit together.

Situation in Poland wasn't magically fixed by one election. Institutions take years to gain authority. Constitutional court is still a joke, judiciary is split into two warring worlds. Additionally supposedly centrist coalition is running to the right for short-term electoral purposes. (completely ignoring that this run itself shifts public opinion to the right).

People "falling" out of helicopters.