The standard edition comes with a speed-enhancing cloak if pre-ordered, but the special edition includes the Adventurer's Pack. That adds character slots, shared storage and gear.
The standard Siege of Mirkwood comes to 14.99 / €19.99, while the special edition is priced higher at £19.99 / €27.99. But the latter does include the Adventurer's Pack which alone goes for $20 in the US. Turbine and Codemasters have recently unveiled bigger bundles.
These Platinum Editions offer the complete LOTRO content to date, including the new Siege of Mirkwood. Standard edition goes for £29.99 / €39.99 and includes the speedy cloak, while the Platinum Special Edition for £34.99 / €49.99 has the Adventurer's Pack.
Both the special editions also come with the speed-boosting cloak and a free mount too. All this combo bundling craziness is listed on the officialwebsite.