Although the source of both types is the same plant - Camellia Sinensis, but green tea leaves are much less processed and are not fermented like black tea. Also they have more delicate and fresh taste.

Green tea extract is a highly concentrated part of the camellia sinensis leaf. Green tea extract is bioflavonoid rich, and one of its main uses is fighting free radicals in your body. Green tea extract has high level of polyphenols (a bioflavonoid), and is a rich source of EGCG. The EGCG in green tea extract protects against digestive and respiratory infections, blocks the actions of carcinogens, which encourages cancer, is anti-bacterial, and also helps lower cholesterol levels.

1. Green Tea contains catechin-polyphenols and caffeine. The catechin-polyphenols restrains the enzyme that tums off catecholamine activity.
2. Catecholamines are responsible for the promotion of fat burning. The caffeine works to support catecholamine production and restrains the enzyme phosphodiesterase.
3. So this means caffeine has the improved ability to burn fatty acids due to the catechinpolyphenols and can act as an inhibitor of the phosphodiesterase enzyme, which turns off fat burning.

Green tea is an un-oxidized, dried tea, mostly found in China and Japan.

There are many health benefits of green tea extract, some of them are:

• Green tea leaf extract is a source of EGCG, a powerful antioxidant 200 times more potent than vitamin E.
• Green tea leaf is anti bacterial, helps lower cholesterol, reduces inflammation, and lowers blood pressure
• Stimulates the immune system, and also helps defend against dental plaque
• Rich in bioflavonoid - protects against digestive and respiratory infections
• Has thermogenic effects that assists in weight loss without causing jitters or other side effects
• Helps decreasing hormone activity and is an effective treatment for acne
• Also help prevent some forms of cancer including colon, pancreatic, and stomach cancer
• Also protects against liver damage

Yes. Their have been many studies done on green tea. Mentioned here are two of them.

Study 1 ( Green Tea and Live Damage): In a study performed by the University of North Carolina, Zhi Zhong and colleagues studied the free radical scavenging effects of green tea leaf extract on problems linked with fatty livers. The study involved drunk rats that went through spree drinking and then put to sleep with their livers removed. Some of these livers were bathed in a green tea extract solution.
These livers were then transplanted into rats with unhealthy livers. The study found that only 13% of the rats that received livers untreated with green tea survived, while 77% that had received a liver treated with green tea extract had survived.

Study 2 ( Green Tea and Acne): In a research studying the effects of green tea on treating acne, researcher Gan Wong et al. (Memorial Medical Center in the Philippines) compared the effects of 3% green tea cream and 4% benzoyl peroxide on moderate to severe acne.

Yes. Green tea has long been used by the Chinese as medicine to treat headaches, body ache, poor digestion, and improve well-being and life expectancy.

EGCG is an antioxidant, which is over 200 times more potent than vitamin E in fighting free radicals and pro-oxidants.

In general, green tea has little or no side effects. However, it does contain caffeine, and individuals with conditions that may be complicated by caffeine intake should consult a medical expert before using green tea extracts. Pregnant women should also consult their doctors before using green tea. Individuals take MAOI inhibitors (anti depressant) should avoid taking green tea.