It is the same for XP Home, Pro, NT, Win2k.
If you do an upgrade installation of XP to a workstation with NT or Win2k installed, the upgrade leaves the original directory name (WINNT) rather than create a new folder (WINDOWS). I note in the interest of completeness that the folder can be called anything you want, there is the option to change it during installation. But the above is a description of what happens with default settings.
This is why you often see a reference in community forums to something like: %windir%\system32\drivers\etc\hosts
This uses the environmental variable %windir% to locate the installation folder for windows.