[dhosek]

Indeed, the French taught in schools is Parisian French, but French as its spoken, e.g., in the south sounds noticeably different.

[Bayart]

Parisian French isn't the same as Standard (Court) French, and it sound different in the South because It's only been the majority language for a century. It's super-imposed on top of another language's phonology. It's not a dialectal continuum thing.

[williamdclt]

Not wrong, but note that the difference is much less than language differences between different English speakers in England, even at short geographical distances.