What is the difference between pressing Alt+Tab and Ctrl+Alt+Tab?

Keyboard shortcuts in Windows

• Alt+Tab Switch between open apps.
• Ctrl+Alt+Tab Use the arrow keys to switch between all open apps.

In other words:

• Alt+Tab Switches between open apps immediately after releasing the Alt key.
• Ctrl+Alt+Tab Opens a quasi-dialogue window where you use the arrow keys to walk over all open apps and you need to press Enter (or click a mouse button) to confirm your choice.

Alt + Tab will let you select the application, and when you release the Alt key, you will be switched to the window you selected. With Ctrl + Alt + Tab, the selection screen will remain displayed, and you will have to press Enter to actually change the focus.

1. Alt + Esc Switches to the next open window

2. Alt + Shift + Esc Switches to the previous open window

3. Alt + Tab Cycles through open windows, and switches to the window when the Alt key is released. This is known as Coolswitch. Pressing Esc cancels switching windows.

4. Alt + Shift + Tab Cycles backwards through open windows, and
   switches to the window when the Alt key is released. This is known as Coolswitch. Pressing Esc cancels switching windows.
5. Ctrl + Alt + Tab Vista: Starts Windows Coolswitch. Use Arrow keys, Tab, or Shift + Tab to navigate and Enter or Space to activate.
   Pressing Esc cancels switching windows.
6. Winkey + T Toggle speech dictation mode. Vista: Cycles through
   Taskbar buttons, Press Enter or Space to activate a window. This is same as Winkey + Tab in older versions.
7. Winkey + Tab Cycles through Taskbar buttons, Press Enter or Space to activate a window. Vista: Cycles through open windows using
   Windows Flip3D. Release keys to activate window. Pressing Esc
   cancels switching windows.
8. Winkey + Ctrl + Tab Cycles through parts of the desktop and
   taskbar. Vista: Starts Windows Flip3D. Use Arrow keys, Tab, or Shift + Tab to navigate and Enter or Space to activate. Pressing Esc cancels switching windows.

From Shortcut Keys and Key Modifiers at https://onedrive.live.com/?id=E2F0CE17A268A4FA%21121&cid=E2F0CE17A268A4FA