What is the difference between confirmation testing and regression testing?

• Confirmation Testing / Re-testing: Verification of a specific defect fix to ensure that the reported problem is resolved and the fix works correctly. Performed after each defect fix.
• Regression Testing: Verification of the existing functionality of the software after making changes (defect fixes, adding new features, configuration changes) to ensure that these changes did not introduce new defects and did not disrupt the previously functioning parts of the system.

Main difference:

Characteristic	Confirmation Testing	Regression Testing
Purpose	To verify the defect fix	To verify that changes did not break the system
Scope	Specific fixed defect	Modules/functionality related and unrelated to changes
When performed	After defect fix	After any code changes
Relation to defect	Related to the identified defect	Not necessarily related to a specific defect, may look for new ones
Test cases	Rechecking the case that found the bug	Sample or all previously passed cases