About ‘Software Quality Assurance'
Software QA involves the entire software development
PROCESS - It is oriented to 'prevention'.
Process is about monitoring and improving the process, making sure that any agreed-upon standards and procedures are followed, and ensuring that problems are found and dealt with.
About ‘Software Testing'
Software Testing involves operation of a system or application under controlled conditions and evaluating the results
TESTING- It is oriented to 'detection'
Controlled conditions should include both normal and abnormal conditions. Testing should intentionally attempt to make things go wrong to determine if things happen when they shouldn't or things don't happen when they should.
QA and testing is a combined responsibility one group or individual. Organizations (Base on the Projects) are very considerably in how they assign responsibility. Also common are project teams that include a mix of testers and developers who work closely together, with overall QA processes monitored by project managers. It will depend on what best fits an organization's size and business structure.