Tea has over hundreds of variety in the world. The majority of which is grown in India, China and Sri Lanka and most of Southeast Asia.
The Tea industry uses the terms Orange Pekoe for all the grades of Black Tea. Means, the whole leaf black Tea can also be called Orange Pekoe Tea.
The term Pekoe in general refers to the unopened terminal leaf bud (tips) in tea flushes.
Depending on whether the Tea leaves have matured or young or only bud, the Orange Pekoe Tea is further graded from the highest to the lowest quality depending on the leaf size, flush and wholeness of Te leaves.
The grades determine the taste, properties and flavour of the Tea. As the young Tea leaves become highest grade of Tea, the matured leaves to be counted as Medium grade and the extra long leaves become the bottom of the grade.