Difference between Regression & Retesting

Regression Testing	Retesting
Regression testing is a type of software testing that intends to ensure that changes like defect fixes or enhancements to the module or application have not affecting unchanged part.	Retesting is done to make sure that the tests cases which failed in last execution are passing after the defects against those failures are fixed.
Regression testing is not carried out on specific defect fixes. It is planned as specific area or full regression testing.	Retesting is carried out based on the defect fixes.
In Regression testing, you can include the test cases which passed earlier. We can say that check the functionality which was working earlier.	In Retesting, you can include the test cases which failed earlier. We can say that check the functionality which was failed in earlier build.
Regression test cases we use are derived from the functional specification, the user manuals, user tutorials, and defect reports in relation to corrected problems.	Test cases for Retesting cannot be prepared before start testing. In Retesting only re-execute the test cases failed in the prior execution.
Automation is the key for regression testing. Manual regression testing tends to get more expensive with each new release. Regression testing is right time to start automating test cases.	You cannot automate the test cases for Retesting.
Defect verification is not comes under Regression testing.	Defect verification is comes under Retesting.
Based on the availability of resources the Regression testing can be carried out parallel with Retesting.	Priority of Retesting over Regression testing is higher, so it is carried out before regression testing.