What is the Difference Between Aspx and Ascx page

The .aspx is the actual page, what the user views in their browser, the .ascx is a custom user
control that is used in the .aspx page. You cannot display a .ascx file in a web browser, just
the .aspx page.

.Aspx:

1 .aspx extension is used for web forms.

2 ASP.NET Page uses the extension .aspx For eg: Default.aspx

3 ASP.NET Page begin with a Page Directive. For eg:
           <%@ Page Language="C#"
           AutoEventWireup="true"
            CodeFile="Default.aspx.cs"
            Inherits="_Default" %>

4 Usercontrol is code which can be used in webforms.

5 ASP.NET Page can be viewed directly in the Browser.

6 ASP.NET Page has a HTML, Body and Form Element

.Ascx:

1 .ascx extension is used for user control .

2 User Control uses the extension .ascx For eg: WebUserControl.ascx.

3 User Control begin with a Control Directive. For eg:
               <%@ Control Language="C#"
                AutoEventWireup="true"
               CodeFile="WebUserControl.ascx.cs"
                Inherits="WebUserControl" %>
4 You can not use webforms in usercontrol.

5 The main advantage of user control is reusability ,u can this control in any number of webforms.

6 User Control cannot be viewed directly in the browser. User Controls are added to WebPages and you view them by requesting a web page in your browser.

7 User Control does not have a HTML, Body or Form element. It is hosted inside an ASP.NET Page.