A test scenario is almost like a story like example "a user enters into the application from login window by entering valid user name and password.After entering he will click on module Payslip and clicks on latest payslip feature to view his latest payslip".Any test scenario will contain a specific goal.
A test case can be derived from a scenario .For the above scenario we can write a test case like :
Test Case # 1:
S.No Steps Expected
1 Open the login window Login window is open
2 Enter valid UN & Pwd Application should be open
3 Click on Payslip Features in payslip should be displayed
4 Click on latest payslip feature It should open latest payslip window
Above is a positive test case and a negative test case can also be prepared.A test case is prepared and executed with a goal to find the hidden defects with different possibilities.