Functional testing focuses on verifying that software functions as expected and meets the specified requirements, such as input validation and business logic. Non-functional testing examines aspects like performance, scalability, and usability to ensure the software meets quality standards in areas aside from functionality.

I prioritize test cases based on factors like risk, functionality importance, and customer requirements. Tests covering critical functionalities or features with the highest risk of failure are prioritized first to ensure key parts of the application are verified early in the testing process.

Quality Assurance is a proactive process focusing on improving and assuring quality in the development process, including methodologies and standards. Quality Control, on the other hand, is reactive and involves the actual testing of the product to identify defects and ensure it meets the required quality standards.

I have extensive experience with various automated testing tools such as Selenium, JUnit, and TestNG. I use these tools to create, execute, and manage automated test cases, which helps increase test coverage and efficiency while allowing for faster feedback on code changes.

Upon discovering a critical bug close to a release, I would immediately communicate the issue to the development team and stakeholders. I would assess the impact and collaborate on a plan, which might include prioritizing a quick fix, delaying the release if necessary, and ensuring rigorous retesting of the affected components.

Key metrics I track include defect density, test coverage, test pass/fail rate, and the mean time to detect and repair defects. These metrics help gauge the software's quality, identify areas for improvement, and measure the effectiveness of the testing processes.