Regression : Testing is conducting on modified build to 
ensure that the modifications are done or not.

Retesting : Testing is conducting on the build with 
multiple set of inputs.

Nuthan Kumar V
Testing Engineer.,

Regression Testing
  Re-execute test on modified build to ensure that bug fix
work and there is no side effect. 

Re-testing : 
  Re-exectuion of a test on same application build with
multiple test data.

Regression-testing:
It is a process of testing the application to check that 
existing functionality is not effective by the bug fixes

Re-Testing:
it is the process of testing that rechecking the bug fixed 
or not
the diff. b/w retesting and regression testing is:
re-test execution on modified build previously failed test 
is a re-testing
re-test execution on modified build previously passed test 
w.r.to functionalities.is aregression test.
if retest pass then only we conduct regression test

Regression and retesting are done on the current build but 
for different reasons.

Regression: This is to ensure that due to the newly 
introduced functionalities, the existing functionality is 
not affected.

Retest: This is to ensure that the defect raised has been 
fixed properly. Defect may be raised against the newly 
introduced functionality or the existing functionality but 
the aim is to ensure that the raised defect has been fixed 
successfully.

Regression Testing: Whenever new code is added to the 
existing software, testing whether the new code has any 
impact on the existing functionalities.

Re testing: After raising the defect, developer fix the bug
testing which is carried out to verify whehther that bug is 
fixed or not is called re testing

Regression testing: is the practice of running an old test 
suite after each change to the system or after each bug fix 
to ensure that no new bug has been introduced due to the 
change or bug fix. To check the ill effect of the software 
to run test cases again on the modified viersion of the 
software.

Retesting: if there would be any error at any point in the 
S/W and to check that particular point of error has been 
solved or not or it is workng properly or not is known as 
retesting.

Regression testing: 
                   Regression testing is done to ensure 
whether the changes made to the application for Fixing a 
Particular "Bug" has not effected the other related 
Functionalities.

Re Testing: 
             Testing the same Application with same 
data,with in the same enviroment

Retesting is performed after defect fixing to ensure defect 
is indeed fixed.

Regression testing is performed after any changes has been 
done to software or environment.It is carried out to make 
sure changes made have not affected system adversly.