Login controls in asp.net provides form authentication. If we implement authentication without login controls then we have to do it from scratch.
Login control allows easy implementation of form authentication without writing much of code. Underneath the controls, the class used for login control is also FormAuthentication class. So instead of creating your own set of user credential validations and issuing of authentication ticket, it is simpler to use asp.net login control. ASP.NET membership mechanism is used in Login controls.