Rebellion added a number of improvements to Sins of a Solar Empire, namely some huge Titan-class ships, as well as doubling factions as each split into Loyalists and Rebels.
Graphics tweaks and AI enhancements are also a part of the package. Kalypso are distributing Sins physically across EMEA territories at varying release schedules.
Sins of a Solar Empire: Rebellion released digitally on PC June 12, 2012.