A privilege is a certain entitlement to immunity granted by the state or another authority to a restricted group, either by birth or on a conditional basis.
Land-titles and taxi medallions are examples of transferable privilege – they can be revoked in certain circumstances.
By contrast, a right is an inherent, irrevocable entitlement held by all citizens or all human beings from the moment of birth.
[1] Etymologically, a privilege (privilegium) means a "private law", or rule relating to a specific individual or institution.
[2] Boniface's abbey of Fulda, to cite an early and prominent example, was granted privilegium, setting the abbot in direct contact with the pope, bypassing the jurisdiction of the local bishop.