Retesting:Testing the same test case again and again after 
the bug fixed

Regression: For the number of test case in the module to be 
tested after executing the test cases for that module if 
any requirement changes we need to execute the entire test 
case for the particular module changed

Retesting :running a test morethan once
Regression testing:It is a test used to verify that already 
tested software is still functioning correctly or not and 
not affected by the test object and the environment.The 
main aim of regression testing is to check whether it has 
any unexpected side effects after fixing a bug.

what we can conclude is if regression testing is a super-
set then retesting is a subset

let me know ur answer

retesting means testing whole document again then it is 
called as retesting.testing once again from starting to 
ending is retesting

testing  particular point where changes taken place.testing 
the particular place where the bug fixed by the 
developer.testing whether that changes effecting on code or 
not it is called as regression testing

regression testing means retesting the previous tested
application to make sure that changes are not cause any side
effects.
Retesting means  restesting the previously fixed defects
check whether it is really fixed or not 
we can conduct regression testing on the modified build
where as restesting is conducted on same build.

ReTesting: The Re-Execution of a test on same application
build with multiple test data is called ReTesting.

Regression Testing: the reexecution of a test on modified
build to ensure bugfix work and possibilities of side effect
occurance .

Consider an Example.
you have modules like add, delete, modify, cancel and ok 
buttons.
you have already 150 test cases for the above.

Now You are going to introduce an other module ie, edit, 
for this You have 50 test cases.

After integrated edit with other modules,  
you check 50 test cases working correctly or not. This is 
Regression Testing,

Now all together you should check all the 150 + 50 test 
cases, ie called Retesting.

Hi ,

    Regression Testing :

                  After getting confirmation that the bug 
is fixed,we would validate if the fixation is giving rise 
to any bugs.

   Retesting: Re-execution of the same TestCases with 
different set of data.

retesting is: u'll test only particular test cases after bug
fixation where u previously found bugs

regression testing: is to again & again test for the impact
on the whole of the modules which can be effected after bug
fixation

Regression testing: the re-execution of all test cases on a 
modified build ,to ensure bug fix work and occurence of any 
side effectives.


Retesting: the re-execution of effected test case on a 
modified build is called retesting.

Regression Testing : In this testing already tested
functionality is once again tested whenever there is a
change i.e. associated with inorder to check whether the
already existed functionality has got affected or not.

Retesting : In this testing already tested functionality is
once again tested with different sets of test data. Before
going to raise any defect it is a tester responsibility to
check whether that defect is a reproduceble or not. So test
engg. must confirm that defect wiht different sets of test data.

Retesting is performed in Regression testing but not vice versa.

Regression Testing : 
                    Testing that is performed after making 
a functional improvement or repair to the program. its 
purpose is to determine if the change has regressed other 
aspects of the program

Retesting : 
            it is testing the same functionality with 
multiple set of data again and again.

Retest in done when you are not sure of the result like not
sure if you followed the given steps or just to make sure
the bug has really occurred. Retest is also done when you
want to show the bug appears on you system if the developer
denies it or show the steps to reproduce the bug.
Other condition when retest is done to see if its been fixed,

On the other hand regression is to check the bug is fixed
and no other bug has occurred  while fixing that.