SurfLiner F59PHI vs F59PHI ND

Just started using trainsim 2014 and the Surliner in particular
Using RW Works to make a custom F59 and hope someone could tell me what the difference is between the F59PHI and the F59PHI-ND.
Thanks
Using RW Works to make a custom F59 and hope someone could tell me what the difference is between the F59PHI and the F59PHI-ND.
Thanks