A RELIGION is a belief in and reverence for a supernatural power accepted as the creator and governor of the universe and having a certain organization and tradition in worshipping such Supreme Being.
In the case of India specifically, Brahmins believe in such Supreme Being and have a unique way of worshipping with certain rituals, which are different from that of the rest of the world.
A TRIBE is a social group bound by common ancestry and ties of consanguinity and affinity; a common language and territory; and characterized by a political and economic organization intermediate between small, family-based bands, and larger chiefdoms.
Some anthropologists believe that tribes developed when more stable and increased economic productivity, brought on by the domestication of plants and animals, allowed more people to live together in a smaller area.
A CASTE is a closed group whose members preferred a particular occupation and a degree of social participation. Marriage outside the caste is prohibited. A specialized labor group may operate as a caste within a society otherwise free of such distinctions (e.g., the ironsmiths in parts of Africa).
According to Webster's unabridged dictionary a CASTE is a race, stock, or breed of men or animals; one of the heriditary classes; a system of social stratification more rigid than class and characterized by hereditary status, endogamy, and social barriers rigidly sanctioned by custom, law or religion; a form of polymorphic social insects that carries out a particular function in the colony.
http://www.vedah.net/manasanskriti/Brahmins.html#1Tribe
