Château and castle are the same word — the French circumflex is a gravestone for the lost 's' in Old French chastel, which English borrowed separately as castle.
A French castle or large country house, especially one giving its name to a wine estate. In wine terminology, the estate that produces and bottles the wine.
From French château (castle, manor), from Old French chastel, from Latin castellum (fort, castle), diminutive of castrum (fortified place, military camp) Key roots: castellum (Latin: "fort, castle"), castrum (Latin: "fortified place, military camp").
Château and castle are the same word — both from Latin castellum. Old French chastel became modern French château (the circumflex marks the lost 's'), while the same Old French chastel was borrowed into English as 'castle.' The circumflex accent in French is often a tombstone for a departed 's' — compare 'hôpital' (hospital