Some of the Web controls are simply replacements for standard HTML controls. How do they add anything to the development experience? They add a more consistent interface to the developer. They also add unique controls for distinct types. And finally, they make it more convenient for developers who don't want to make any changes on the client side.
Examples of the simple replacements for HTML elements are RadioButton , CheckBox , and Button controls. Although they don't really provide any more functionality than their equivalent HTML counterparts, they do provide a more unified programming interface and object model.