Difference between normal usecase and an extended usecase

Could someone describe me the difference between what a normal usecase does and what an extended usecase does.I have posted my two usecases, a normal usecase and an extended usecase. I actually don't find a lot of difference between what they show

My normal usecase is:
4.1.2 Add users
Brief Description
The admin accesses the admin panel and adds users with different roles. These users are the storekeeper and POS staff of the business.
The admin has been logged in to the system
Basic Path
1. The admin clicks on ‘Add User’ button
2. A form popups where the admin has to fill details regarding the type of user, his role and his general information
3. The admin confirms to add the user.
4. The system validates the form.
5. User is added
New user is added in the system.

And my extended use case is :

Use case: Add users
Actors: Admin
Purpose: To add users with different roles.
Overview: Admin has to add users to the database so that other staffs can access the system to perform their work
Cross references: Functions: IFS2 (Add users)
Flow of events
Actor Action

1. This use case begins when the admin wants to add staff information so that they can access the system
2. Admin tries to add a new user
4. Provides details of the new user and

System Response
3. Asks to enter details of the new user (username, password, names, etc)
5. Validates and adds the user

Alternative flow of events
Line 5: Invalid user details. Indicate error. Return to step 4