Admin vs application page

Question

In SharePoint, there are admin and application pages.

What's the difference between an admin and an application page?

Answer 1

Admin Pages:

Admin pages are typically used to extend central administration functionality and links to such pages are given in central administration site.

Central Admin Web site uses a virtual directory named /_admin that is similar to the /_layouts virtual directory of content sites. The administrative virtual directory is mapped physically to the {SharePoint Root}\Template\Admin directory, which is where you can place custom administration pages. Pages that are located in this directory are associated with the configuration database (as opposed to content database).

Application Pages

Application Pages are typically used to extend site collection administration functionality (or provide application specific functionality). Links to such pages are typically given in Site Collection level or web level administration pages depending upon the scope.

Application Pages uses a virtual directory named /_layouts and OTB, it is mapped physically to the {SharePoint Root}\Template\LAYOUTS directory, which is where you can place custom Application pages.

As a general rule, if your functionality is reading/updating configuration database, create a admin page in _admins virtual directory and if it deals with content database, create an application page in _layouts virtual directory.

Answer 2

Application Pages:

Application Pages are available available through the site collection. You can't modify the application pages using SharePoint designer. Application also called a layout pages because its deployed and _layouts/settings.aspx

Admin Pages:

Admin pages that are available in Central admin Site. Admin pages are used to perform that administrative task like creating web Application , content database , attaching content database etc. Pages reside under 14\TEMPLATE\ADMIN example _admin/WebApplicationList.aspx.