My background is system analyst, but while learning UX processes I have faced several things that confuse me; one of them is the differences between User Goal that is used in usability testing and Use Case that are typically used in UML.
Alistair Cockburn described the structure of a use case in his book Writing Effective Use Cases, e.g:
As a [user] I want to perform [some task] to meet [some goal].
[user] can be a person or a system
[some task] is the activity
[some goal] is what you want to achieve
A use case should be written in non-technical language. A use case may also contain additional things like steps and constraints, etc, but the core use case statement is very similar to a UX user goal.
A user goal describes what the user is trying to do, a use case describes how they do it.
- Goal: Buy a car
- Task Scenario: "You've decided to buy a new car for your family with a budget of £20,000."
Use case (this is highly simplified):
- User clicks "Buy a car" navigation link
- They change the max price to £20,000
- They filter out smaller cars and view specific details for each car
- They click "Buy"
In the UX field you're much more likely to see user stories and scenarios than traditional use cases.
This article on wikipedia actually does a good job of explaining Use Case. If you take the time to read it, you'll find there are a number of references to user goals and the examples and steps provided help to differentiate between the two.
User Goal is the Result that user wants to achieve.
Use Case is the Scenario/way in which user is going to achieve that goal.
Here is an example.
You want to reach New York city. This is your User Goal.
You book a flight ticket. Pay for it. Get on the plane. Transit. Reach destination. This is your Use Case.
In short Use Case is series of related events/actions taken by you. While User Goal is the pre-defined outcome of this related actions.