Green Tea. - Though the green tea and black tea are leaves of same plant, Camellia sinensis. only the processing makes the difference.EGCG is a powerful anti-oxidant found in tea leaves.Green tea leaves are steamed, which prevents the EGCG compound from being oxidized. By contrast, black tea leaves are made from fermented leaves, which results in the EGCG being converted into other compounds that are not nearly as effective in preventing and fighting various diseases.