WHAT IS OCCITANIA?
Occitany is not a state and has never actually been one: it is a cultural and linguistic area of Europe, which for thousands of years has been united by a natural language, the Romance language called Occitan.

What is the difference between «patois» (or «patés») and Occitan?

As opposed to French which is a national language, the word «patois» is derogatory, to indicate a non-official language or dialect. This term was common during the time of the French Revolution, as part of the project launched by Abbé Grégoire for the “elimination of patois” in France.
The term Occitan is used to describe the language as a whole with all its differences: but those who speak «patois» in fact speak Occitan.