Difference between Use Case and Test Case

Use Case

Use case describes someone interact with software/system to achieve certain goal.
It is defined in business requirement document before coding.

Test Case

Test case refers to detail test description written to guide tester completing testing execution in order to determine whether the function under testing pass or fail, it contains the following:

test case ID
test description
Pre-conditions
Test steps
Expected outcome
Compatibility
and etc.

When asking the question, what the difference between use case and test case, the answer can be:

1. Use case and test case are developed at different stage:
    Use case is developed at beginning when Business Analyst analysis customer requirement and summarize up with use case and use diagrams to describe functions required.
    Test case is designed by testers after test plan is approved by stakeholders.

2. User case and test case are for different audience.
    Use case is written for customer, client, managers, business analysts.

    Test case is mainly written for developers and testers.