Vadakalai and Thenkalai are two sub-sects within the Sri Vaishnava tradition of Hinduism that have some differences in their beliefs and practices.

Vadakalai, which translates to “northern group” in Tamil, is a sub-sect that originated in the northern parts of Tamil Nadu, while Thenkalai, which means “southern group,” originated in the southern regions of Tamil Nadu. Some of the main differences between the two sub-sects include:

1. Prabandham: Vadakalai considers the 4000 verses of the Divya Prabandham, which are hymns sung by the Alvars, to be authoritative texts. Thenkalai, on the other hand, considers the Tamil translation of the Sanskrit Vedas, called the Dravida Veda, to be equally authoritative.

2. Pancha Samskaram: Vadakalai requires that a person undergoes the Pancha Samskaram, which is a set of five rituals, including the sacred thread ceremony, to become a member of the Sri Vaishnava community. Thenkalai, on the other hand, does not consider these rituals to be necessary.

3. Idol Worship: Vadakalai emphasizes the worship of idol form of Lord Vishnu and his consort Lakshmi, while Thenkalai gives more importance to the worship of the divine sound or mantra of the Lord, known as the “Ashtakshara mantra.”

4. Food habits: Vadakalai follows a vegetarian diet that includes the consumption of milk and milk products, while Thenkalai does not consider milk and milk products to be vegetarian and follows a strictly vegan diet.

Despite these differences, both sub-sects share a common belief in the Sri Vaishnava philosophy and devotion to Lord Vishnu and his consort, Mahalakshmi. Both sub-sects also have their own respective Acharyas, or spiritual leaders, and have contributed significantly to the development and propagation of the Sri Vaishnava tradition.