test case: to test the functionality of a particular 
object. eg : for login
data: user name and password
test scenario :  to test the functionality of a group of 
objects to get the result. eg: for login 
1.login successful
2.login failed
so these two test cases together contribute a scenario for 
login.

Hi!
Difference between Test Case & Test Scenario


Test Case : Is a document which describes the input, 
Action/Event and expected response to determine whether the 
particular functionality of the application is working fine.
It is a commonly used term for a specific test. This is 
usually the smallest unit of testing. A Test Case will 
consist of information such as requirements testing, test 
steps, verification steps, prerequisites, outputs, test 
environment, etc. A set of inputs, execution preconditions, 
and expected outcomes developed for a particular objective, 
such as to exercise a particular program path or to verify 
compliance with a specific requirement. 

Test Scenario : A set of test cases that ensure that the 
business process flows are tested from end to end. They may 
be independent tests or a series of tests that follow each 
other, each dependent on the output of the previous one.
Definition of a set of test cases or test scripts and the 
sequence in which they are to be executed.

test case is a document which contain
test case name
prepared by
reviewed by
approved by
data of created
date of approval
date of reviewed
test design steps,  test data, expected pass/fail, comments

identifying testable item is a test scenario

Test Case: A specification that describes the goals of a 
test, the results that the test might produce, the 
circumstances in which it will be run, and how it should be 
implemented.

Test Scenario: Definition of a set of test cases or test 
scripts and the sequence in which they are to be executed.

test scenario is process which insist the tester to think 
beyond limits , think about  the complex  area of the 
application .  There are lot of types of test scenario like 
usecase senario . Let us take one example for login mail 
account , check amil , give reply to some mails and 
logoff , we have to write scenario on this then we will 
write like this way user A went to office ,He login to his 
his mail account , then he checks mail and gives reply to 
some mails then user A logoff . It is little bit story 
type .

The tase cases consists of steps / action to be performed , 
expected result and actual result , severity and priority .