Works in the public domain are those whose intellectual property rights have expired, have been forfeited, or are inapplicable.
For example, the works of Shakespeare and Beethoven, most of the early silent films, the formulae of Newtonian physics, the Serpent encryption algorithm and powered flight are all now in the public domain.
The term is not normally applied to situations where the creator of a work retains residual rights, in which case use of the work is referred to as "under license" or "with permission". (Wikipedia)
Creative Commons (CC) is a non-profit organization devoted to expanding the range of creative works available for others to build upon legally and to share.
The organization has released several copyright-licenses known as Creative Commons licenses free of charge to the public. These licenses allow creators to communicate which rights they reserve, and which rights they waive for the benefit of recipients or other creators. An easy-to-understand one-page explanation of rights, with associated visual symbols, explains the specifics of each Creative Commons license.
Creative Commons licenses do not replace copyright, but are based upon it.
They replace individual negotiations for specific rights between copyright owner (licensor) and licensee, which are necessary under an "all rights reserved" copyright management, with a "some rights reserved" management employing standardized licenses for re-use cases where no commercial compensation is sought by the copyright owner. (Wikipedia)
Open Government Licence (OGL)
The Controller of Her Majesty's Stationery Office (HMSO) has developed this licence as a tool to enable Information Providers in the public sector to license the use and re-use of their Information under a common open licence.
The Controller invites public sector bodies owning their own copyright and database rights to permit the use of their Information under this licence.