SQL Server 2008 has come with two mechanism for tracking and recording the database changes.
1. Change Tracking
2. Change Data Capture (CDC)
This new mechanisms has reduced the work associated with data security and compliance. By introducing these new auditing mechanisms MICROSOFT has reduced the overhead of developing custom tracking solutions. Change Data Capture and Change Tracking enable applications to determine the all insert, update and delete operations on all user tables.
Difference between Change Data Capture (CDC) and Change Tracking :
1. Change tracking only captures that rows in a table were changed, but does not capture the data that was changed, whereas Change data captures both changes made and the actual data that was changed.
2. Change Tracking supports synchronous tracking mechanism which is used to track the changes. Change Data Capture (CDC) uses the asynchronous process that reads the transaction log.
3. Change Tracking has minimal impact on the system. Change Data Capture (CDC) as low impact on system as it uses the asynchronous process by reading the transaction log.
4. Change Tracking supports real time synchronization as it runs the synchronous process. Change Data Capture (CDC) run on asynchronous process.
Microsoft has published a nice article on Comparing Change Data Capture (CDC) and Change Tracking.http://msdn.microsoft.com/en-us/library/cc280519.aspx