Welcome to the Apache Friends network.
For the file that works, there is most likely a file called:
For example, if you were trying phpinfo.php in your PhpTestScripts folder, then there's probably an identical phpinfo.php page in the xampp folder, which is why you're getting the expected code.
Try testing on the link Izzy gave you, since he beat me to it.
If you want to go to your folder without always typing the folder name, see this thread