Severity indicates the seriousness of the defect.
Severity types are Critical, Major, Moderate, Minor, Cosmetic
Priority indicates how quickly the defect needs to be fixed.
Priority types are High, Medium, Low.
Low Severity and Low Priority: A cosmetic error in a page which is not important to users.
High Severity and High Priority: An error in the login feature which does not allow user to login to application or a server error in the web application.
Low Severity and High Priority : The spelling mistakes that happens on the cover page or heading or title of an application.
High Severity and Low Priority: A page access error which page is rarely used by users.