Real tea is derived from a particular plant (Camellia sinensis) and includes only four varieties: green, black, white, and oolong. Anything else (like herbal “tea”) is an infusion of a different plant and isn’t technically tea.
Green Tea - made with steamed leaves, has antioxidents which interfere with the growth of bladder, lung stomach, pancreatic and colorectal cancers; prevent clogging of the arteries, burn fat, couteract oxidative stress on the brain, reduce risk of neurologial disorders like Alzheimer's and Parkinson's diseases, reduce risk of stroke and improve cholesterol levels.
Black Tea - made with fermented leaves, has the highest caffeine contect and forms the basis for flavored teas like chai and some instant teas. Studies have shown that black tea may protect lungs from damage caused by exposure to cigarette smoke. It may also reduce the risk of stroke.
White Tea - uncured and unfermented. One study showed that white tea has the most potent anticanver peroperties compared to more processed teas.
Oolong Tea. In an animals study, those given antioxidants from oolong tea were found to have lower levels of bad cholesterol.