Black and green tea are made from the leaves of Camelia Sinensis plant. The key difference between the two is that black tea is fully oxidized and green tea is not.
To prepare black tea, the plucked leaves go through the process of withering which naturally reduces the amount of water in the plant. The leaves are then set aside to oxidize in a process called fermentation. This leads to changes in the chemical composition of the tea leaves. The longer the leaves undergo the oxidation process the darker the colour is. A lengthy oxidation process gives the black tea its distinct bold flavour.
Green tea is prepared in a similar way and undergoes the same withering process as black tea; however, the difference lies in the fermentation. The green tea leaves are allowed to wither slightly but are then either pan-fried or steamed or oven-dried to prevent oxidation. Since the leaves do not undergo fermentation, they retain their green colour and produce grassy, vegetative lighter taste.
Both black tea leaves and green tea leaves contain same amount of flavonoids -important anti-oxidants which promote several health effects. The difference is that green tea contains much more catechins – 3.5 times more. Black tea contains 100 times more theaflavins and 45 times more thearubigins.
Green tea has 25-35 mg of caffeine and also a chemical compound L-theanine, which offers increased alertness and mental acuity without the jittery side effects of caffeine. Green tea has the ability to make you feel awake and alert with a degree of calmness due to the presence of L-theanine.
Black tea has 50-90 mg of caffeine on average, making it a good choice for extra energy boost during the day.
Both Black and green tea contain powerful compounds offering a host of health benefits. Both help to keep immune system healthy, promote heart heath, cognitive function, and aid in weight loss. At the end of the day, it really comes down to preference and taste.
My recommendation is to experience both green and black teas from different regions to discover the nuances of the flavour profile. One must drink tea to relish the benefits for their mind, body and soul, and both green and black teas can provide those.