Once after completing the script execution, QTP will generate the results in a hierarchy of tree structure. It will show the Checkpoint Results. And it will show the results from custom statements such as Reporter.ReportEvent also.
Normally, it will be in xml format. We can save results as HTML file also.
The result viewer is having option to filter the required results based on many criteria such as pass, fail and warning.
And, if we enable storing screenshots, the result window will show the difference between the Actual results and the Expected results in visual manner also. It will be easy to recognize any error in result screen.