In the French wine classification, what is the difference between AOC and AOP?
Answer : none!
It's just that the AOC - Appellation d'Origine Contrôlée - is a French label, while the AOP - Appellation d'origine Protégée - is ... European.
But both refer to the set of rules a wine needs to comply with in order to be labelled after a given appellation (e.g. Sancerre).
France boasts over 300 appellations. And each one has rules regarding many aspects of the wine production process such as grape varieties, vines localization, yields, aging process,...