Assam black tea and Ceylon black tea are both belong to the tea category of black tea, they have some differences in origin, production process and taste.

1. Different places of origin: Assam black tea is produced in Assam, India, while Ceylon black tea is produced in Sri Lanka.

2. The production process is different: Assam black tea is generally made of fully fermented process, the tea broth is dark red, with a strong malt and fruity aroma; while Ceylon black tea is generally made of partially fermented process, the tea broth is reddish-brown or brownish, with citrus and peach aroma.

3. The taste is different: Assam black tea has a strong taste and a high degree of bitterness, and requires the addition of milk and sugar; Ceylon black tea is relatively soft, the tea broth is smooth and sweet, and is usually consumed without adding other ingredients.

In short, the difference between Assam black tea and Ceylon black tea lies in the origin, production process and taste, etc., and consumers can choose according to their own tastes.