Testing an application basic feature and critical feature is a Smoke testing. Testing an application bug fixes and new feature is a sanity testing. Testing the Impact area of an application after a Defect Fix and changes can be done in Adding Modifying Deleting. Unit testing is kind of White box testing Integration testing is kind of Black box testing.Big Bang approach is Integration testing all modules integrated together. Testing an application from end to end just like real user is testing environment similar to production environment is system testing.