Civil 3D 2013 and Civil 3D 2014 Interoperability
For previous versions of Civil 3D, the dwg file format is year specific. Civil 3D .dwg files opened in a newer version could not be downgraded without losing the modeled data, or using LandXML to translate models. Civil 3D 2013 can open and work with drawings saved in 2014, no save as or export is required. This comes with a few caveats – 2013 cannot edit pressure networks created in 2014, and data shortcuts are static (they don’t update when the referenced file is updated).
Data Reference Caching
Data references other than surfaces are now saved in directly in a drawing file. This can lead to a lot of performance benefits, especially when working with files in remote locations.
Pressure Pipe Networks
Data references are now available for pressure pipe networks. You can use data shortcuts to reference your pressure pipe networks in other drawings. This was an important feature missing from Civil 3D 2013 pressure pipes.
Windows 8 Support
Civil 3D 2014 is supported on 64-bit Windows 8. It is not supported on Windows XP.
See the Autodesk Help Website for a complete list of other Civil 3D 2014 changes.