| User Control | Custom Control |
| Stored as .ascx extension. | It is a .dll extension. |
| They have a visual interface. | These controls don't have a visual interface. |
| Do not appear in the toolbox and does not have design support; loaded at runtime. | Can be added to the toolbox and used in various applications without re-compilation. |
| If we need controls particular to a website, user control is a good option. | Custom controls can be created to be used across various applications. |