A foudre is not a large barrel but a new ageing concept with several centuries of history.
Due to their larger size, foudres allow for a lower ratio between the contact surface of the wine and the wood, which can result in a gentler extraction of compounds from the wood and a more gradual oxidation of the wine. This makes them ideal for wine styles that require prolonged ageing and a more subtle wood influence. Very suitable for white and red wines that need more volume on the palate.