Term	Definition
Principal	A principal identifies an entity (i.e., a framework or an operator) that interacts with Mesos. In UNIX terms a Principal is the same as a username
Role (or Group Membership)	A role, on the other hand, is used to associate resources with frameworks in various ways. Think of a role like groups in UNIX.
Secret
Entity	A container which can either hold a particular value or specity the special types ANY or NONE.