1) Black box testing -It is done by test engineers. White box testing -It is done by the developer. 2)Black box testing -Code is not visible. White box testing -Code is visible. 3)Black box testing -Here tester will check the functionality of the application. White box testing -Here developer will check Weather the code is working. 4)Black box testing -It is also called as closed box testing. White box testing -It is also called as open box testing. Severity - Simple answer " If the application is on customer's hand and How it going to impact on the customer business workflow that is Severity. Priority - "If the application is on admin hand and How it is impacting on the admin business workflow that is Priority".