Ctrl vs CapsLock
Both CTRL and CapsLock are Keys on computer keyboards.
Different keyboards put these keys in different places.
The Microsoft Natural keyboard for example has a larger CTRL key on the bottom left corner.
Also, the caps lock key doesn't have to be a caps lock key. It's a very useful key to map as a mode changer in vim.
 Swapping Ctrl and Caps Lock
Run "setxkbmap -option ctrl:nocaps" to make both keys Control, or ctrl:swapcaps to swap them.
This can be made system-wide by placing the following in /etc/X11/Xorg.conf.d/keyboard.conf:
- Option "XkbOptions" "ctrl:swapcaps"
 Microsoft Windows
Or save the following with a .reg extension and open it (it will be merged into the registry) then reboot.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout] "Scancode Map"=hex:00,00,00,00,00,00,00,00,02,00,00,00,1d,00,3a,00,00,00,00,00
 Mac OS X
- System Preferences > Keyboard & Mouse > Modifier Keys