Answer:
One of CC’s goals is ensuring that all of its legal tools work globally, so that anyone anywhere in the world can share their work on globally standard terms. To this end, CC offers a core suite of six international copyright licenses (formerly called the “unported”) that are drafted based largely on various international treaties governing copyright, taking into account as many jurisdiction-specific legal issues as possible. The latest version (4.0) has been drafted with particular attention to the needs of international enforceability.
For version 3.0 and earlier, Creative Commons has also offered ported versions of its six core licenses for many jurisdictions (which usually correspond to countries, but not always).
These ported licenses are based on the international license suite but have been modified to reflect local nuances in the expression of legal terms and conditions, drafting protocols, and language. The ported licenses and the international licenses are all intended to be legally effective everywhere. CC expects that few, if any, ports will be necessary for 4.0.
CC recommends that you take advantage of the improvements in the 4.0 suite explained on the license versions page unless there are particular considerations you are aware of that would require a ported license.