The difference between french-style oak and Piedmont-style oak ... 225 litres versus 10,600 litres. The former are usually new every year, the latter are 50 years old in this case. Both are used to make Barolo.
That's not a barrel:
This is a barrel:
By the by, for French oak, the trees have to be around 150 years old. That was the legal minimum until a few years ago, when the age was lowered slightly, sometimes to around 120 or 130 years old. And for one majestic 150 year old oak tree, you will be lucky to get three oak barrels - more usually two. Of course the off-cuts go into making furniture and other wood products, but that still means a lot of tree for a little barrel.