Even though the BDC made it relatively easy to create read-only SOLUTIONS that display data in the Business Data List Web Part, it was not so simple to create a solution that enabled users to make changes and write that data back to the external store.BCS, on the other hand, provides you with Read-Write capable CONNECTIVITY from Client and Server to Database, WCF/Web Services and .Net Sources. A Developer can now USE SharePoint DESIGNER 2010 and VS 2010 rapid development tools to access external data.

Even though the BDC made it relatively easy to create read-only solutions that display data in the Business Data List Web Part, it was not so simple to create a solution that enabled users to make changes and write that data back to the external store.BCS, on the other hand, provides you with Read-Write capable connectivity from Client and Server to Database, WCF/Web Services and .Net Sources. A Developer can now use SharePoint Designer 2010 and VS 2010 rapid development tools to access external data.