Explorer (located in C:\Windows\Explorer.exe by default) is the Windows System program used to view files and folders. Internet Explorer (IE) is used to view website, it is possible to use IE to view folders but this is not common and must be manually implemented.
Wikipedia
File Explorer, previously known as and still sometimes called Windows Explorer, is a file manager application and default desktop environment that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It provides a graphical user interface for accessing the file systems. It is also the component of the operating system that presents many user interface items on the screen such as the taskbar and desktop. Controlling the computer is possible without File Explorer running (for example, the File ▸ Run command in Task Manager on NT-derived versions of Windows will function without it, as will commands typed in a command prompt window). After the name change that was introduced in Windows 8, Windows Explorer name can still be seen when you look for it in the Windows Task Manager.