White pepper starts as the same berry as black. It is picked riper, then soaked in running water for several days until the outer skin softens enough to be rubbed away. What is left is the pale inner seed.
Removing that skin removes most of the fruity, floral character and leaves the heat and a deep earthy pungency underneath. That is why cooks who know both treat them as two separate spices rather than a pair.
It is used across Sri Lankan and Southeast Asian cooking wherever black flecks would spoil the appearance of a pale dish, and wherever that particular earthy pungency is the point.
The retting process is slow and labour intensive, which is why white pepper costs more than black despite coming from the same vine.
