The leaves are steamed or fried to inactivate oxidation, and then dried.

White tea therefore retains the high concentrations of catechins which are present in fresh tea leaves.

The buds may also be shielded from sunlight during growth to reduce formation of chlorophyll.

Green tea is made from more mature tea leaves than white tea, and may be withered prior to steaming or firing.

Although green tea is also rich in catechins, it may have different catechin profiles than white tea.

For white tea, the little buds that form on the plant are covered with silver hairs that give the young leaves a white appearance.

The leaves come from a number of varieties of tea cultivars, the most popular are Da Bai (Large White), Xiao Bai (Small White), Narcissus and Chaicha bushes.

White tea is steamed and dried almost immediately after harvesting (sometimes before even leaving the fields).

This method of minimal processing may account for white tea's higher than normal medical benefits.

(https://www.sciencedaily.com/terms/white_tea.htm)