When PXE booting Bios or UEFI systems one model will boot and the other won't boot.    

If DHCP option 66 or 67 are being used this can cause an issue.   These are known as the PXE Force Mode entries for a DHCP server and will direct the server to deliver only a UEFI or a BIOS compatible PXE package.  If option 66 and 67 are in use they should be removed and IP Helpers set up on the switches to point to the PXE server.  

There is another issue that may arise.  It is possible that in the  PXE server's eXpress\Deployment Server\PXE\Images\BStrap\x86 and x64 folders don't have a bstrap.efi file in them. 

NBP filename is BStrap\x64\BStrap.efi
NBP filesize is 0 Bytes
PXE-E32: Client received TFTP error from server. 

It may be that when installing PXE to a server other than the ghost server that the eXpress\Deployment Server\PXE\Images\BStrap\x86 and x64 folders did not get populated with the BStrap.efi

Locate the BStrap.efi on the Ghost server and copy it to the eXpress\Deployment Server\PXE\Images\BStrap\x86pc and x64 folder on the PXE server.  This should allow for booting both UEFI and Bios based systems to PXE now.