Re-Testing: After a defect is detected and fixed, the software should be retested to confirm that the original defect has been successfully removed. This is called Confirmation Testing or Re-TestingRegression testing: Testing your software application when it undergoes a code change to ensure that the new code has not affected other parts of the software.
Re-Testing: Testing activity to check if the errors are fixed. Regression Testing: Testing activity to ensure that the fixing of a bug has not introduced new errors