In wines today's primary flavour changer is oak, along with other woods, such as chestnut, that are used for barrels. However as the french oak supplies are diminishing eventually other sources will be required.
Each of these have different characteristics :
Yes all that from the barrel .
However then we also havethe toasting of the barrel ,
Light Medium and Heavy ....lighter toasts emphasize the fruit while heavier toasting develops more smoky, woody, and spicy flavours.