All tea comes from the Camellia Sinensis plant. What makes each tea different is the way it has been processed.
This tea goes through the most processing. Once the leaves are picked they are left out in the sun to become slightly wilted. The leaves are then rolled to break open their tissue. The inner chemicals react with the air and begin to ferment. During the fermentation, the leaves darken and change from green to red and finally to black. After the fermenting is complete, the leaves are dried and them packaged.
Green tea is from the same plant as (Camellia Sinensis.) as all other teas. After the tea leaves are plucked and sorted, they are either steamed or pan fired. Green tea does not go through the oxidation (fermentation) process. Green tea does have less caffeine than black tea. The leaves are often rolled into different shapes before drying. Sencha tea is rolled into fine strands, while gunpowder tea leaves are rolled into pellets. Many Chinese green teas are painstakingly shaped and tied. Once the leaves are shaped, they are dried and packaged. Green tea also has HGCG; the most powerful antioxidant known. This can only be found in green tea.
Oolong tea, like black tea goes through a withering stage (wilting). The difference is the oolong tea, goes through a shorter stage and the leaves are fired directly after that to prevent continued oxidation (fermentation.) The leaves can range from being almost black to dark green depending on when oxidation is stopped. The longer the leaves are oxidized the closer to black tea they will become. Formosa Oolong is an Amber Oolong with a rich amber cup that is a little toasty tasting. Se Chung leaves are not allowed to oxidize as long, so the leaves have a dark green appearance and produce a light yellow cup with hints of sweetness. Oolongs are categorized between green and black teas and range dramatically in oxidation, between 15-75%. The length of oxidation is responsible for the tea's character, taste, and caffeine content as well as the color of the leaf and the liquor in your cup. Oolongs that are oxidized for a longer period are considered dark oolongs, while those with less oxidation are referred to as green oolong.
White Tea .
White tea is the least processed tea. The leaves are picked early in the year while the tiny white hairs are still visible on the leaves and the bud is still closed. Only the top leaf and a bud are picked from the plant. The leaves are then allowed to dry in the sun; they are not steamed or pan fired like green tea. If mechanical drying is required for a white tea, they are baked. This produces a light cup usually a very pale yellow with a light and lightly sweet taste. Look for quality in the number of buds present. The buds should have the appearance of tiny white hairs and will be silver and white in color. Teas labeled "needle" should be 99% bud. Non needle white teas will be bulky with a bright, crisp leaf color.
Tea Pu'erh is a large leaf tea variety. It is grown and picked throughout the year. Although dark Pu'erh tastes much like black tea, it is not black or oolong tea, but falls into a category of its own. Pu'erh is processed much like black tea with the exception of a couple steps. The tea is picked, processed and partially fired allowing the leaves to retain moisture. The slightly moist tea is then piled. The natural bacterium on the leaves creates a reaction similar to that of a compost pile. The tea is then aged, in special underground rooms or caves, adding to its unique character. One of the most significant distinctions of this tea is that it gets better over time. These aged teas are prized and can be found in vintages, like wine, some dating back 40 to 50 to 100 years.