Most of the wine world use American and French oak barrels for aging their wines, giving them a deeper, more complex flavour, as the wine takes on aromatic characteristics from the oak barrel it is interred within. Every barrel is different - every resultant wine is also slightly different. However, the main difference between the two barrel varieties is that American oak is stronger and harsher in flavour (and therefore wines are left less time in these barrels - perhaps six months), while French barrels are more subtle and complex (wines in Argentina remain in these barrels for typically six months to two, three or even four years, some even longer).