Difference between HTML control and Web Server control
HTML controls are the native browser elements and they are part of HTML language. These are client side controls which is accessible only in the HTML page, so it will improve the performance of the web page. HTML controls on an ASP.NET Web page are not available to the web server.
HTML Server controls
You can add the attribute runat="server" to any HTML control, such cases it will be an HTML server control. These controls map directly to html tags and without runat="server" it cannot access the control in code behind.
Web Server Controls or ASP.NET controls
Web Server Controls are group of controls derived directly from the System.Web.UI.WebControls base class. They are executed on the server side and output HTML sent back to the client browser. These controls are programmable and reusable that can perform function as the ordinary HTML controls. Web Server Controls can detect the target browser's capabilities and render themselves accordingly.
WServer Control Advantages
Server controls are easy to use and manage but HTML controls are not. Server control events are handled in the server side whereas HTML control events are handled in the client side browser only . It can maintain data across each requests using view state whereas HTML controls have no such mechanism to store data between user requests.