The Camellia sinensis plant, which produces all tea, is the same. Different levels of processing result in different varieties of tea, ranging from the most processed black tea to the least processed white tea, oolong tea, and green tea. Flavanoids are the name for the antioxidants found in tea.
Catechins and theaflavins in green tea and black tea
Tea contains a kind of flavanoids known as catechins. Green tea has six primary catechins: catechin, gallocatechin, epicatechin, epigallcatechin, epicatechingallate, and epigallocatechin gallate, which is the most significant (EGCg or EGCG).
Catechins are transformed into theaflavins (TF1), theaflavin-3-gallate (TF2A), theaflavin-3′-gallate (TF2B), and theaflavin-3,3′-digallate during the fermentation process used to make black tea and oolong tea (TF3). These also have antioxidant qualities like catechins do.