A custom control is a loosely joined control defined in a class that stems from control. The UI of the custom control is usually demarcated in a resource wordlist inside the source file. They are fashioned according to the requirement of the business.
If you want to change the functionality of the existing controls, such as button or label, you can directly procure the new class with the current classes and can change their conduct. We can create themes for custom control and reuse them in different projects.
The base user control is almost like a custom control that you obtain to produce a control UI specific to your application. It provides the reusability of design and is made the same way as a web form. User controls are advantageous if they must be used only for a particular website. They have a visual interface.