Do you guys know what changed in the 2014 edition?
Someone correct me if I'm wrong, but I believe the older Big Boxes had expansions 1 and 2 plus a handful of mini-expansions, whereas the new Big Box (5) has expansions 1, 2 and 8 (and is probably better value).
Darius I – 73rd Great Khan of the Illustrius Barbarian Horde, Duque San Lorenzo, Marquis de Feltón, Chief of the Zayante, Baron von Whaleyland, Lord Kennedy
There's a breakdown of the Big Box contents on the main Carcassonne page.
Both sets contain
- the base game;
- Inns & Cathedrals (including the 6th Meeple set);
- Traders and Builders.
I only own the most recent big box (#5) so can't speak for the contents of the other set, but mine does not contain the canvas bag that I think you would normally get with a standalone copy of Inns & Cathedrals. It's not necessary for the game, but would have been nice to have.
The older box (#4) contains
- Corn Circles II
- Mage & Witch
- The Ferries
- The Flying Machines
- The Gold Mines
- The Messengers
- The Robbers
I haven't tried any of these expansions but they're all quite small I believe.
The newer box contains
- The River*
- Hills and Sheep (again, without the canvas bag though)
- Extra Meeple sets to allow a 7th (purple) and 8th (pink) player.
- The Wheel of Fortune**
* The River contained in the Big Box set has some extra features which tie in with the Hills and Sheep expansion that you don't get (as far as I know) if you buy the River anywhere else. You can ignore these if you aren't playing with Hills and Sheep, but it's nice to have as Carcasonne expansions don't normally really integrate like this.
** The Wheel of Fortune is a "standalone Carcassonne game" which normally includes the normal base game tiles along with some extras. Strictly speaking therefore Big Box 5 either doesn't actually include the base game and instead includes a full copy of Wheel of Fortune, or includes only the extra tiles in Wheel of Fortune, depending on how you look at it. There's nothing stopping you from playing unexpanded carcassonne using only the tiles from the base game (which are which are clearly and helpfully marked in this set).
For my money I'd say the new box is better value? But I haven't played the expansions in the older set.