Over time, the metadata for a WCF service may change, requiring that the service reference be updated.

.NET Updating Service Reference:

• In Solution Explorer, right-click the service reference and then click Update Service Reference.
  
  A progress dialog box is displayed while the reference is updated from its original location, and the service client is regenerated to reflect any changes in the metadata.

Updating Web Reference:

• In Solution Explorer, open your project's App_WebReferences folder and click the node for the Web reference you want to update.
  
  
• Right-click the reference and click Update Web Reference.
  
  The new files for the XML Web service are downloaded to your project. Information for the XML Web service is updated within your project.