> French person here : no differences, we pronounce them all é and we don't care.

No we don't.

In the South the é sound is more common while in the North they tend to pronounce the è very 'correctly', but that does not apply to all words.

For instance the way someone pronounces "après". In the South it is quite common to pronounce it pretty much like if it was written "aprés". Same goes for "est", e.g. il est(é) vs il est(è).

That's how you recognise a Parisian in Marseille because they have an "accent pointu" ;)