They are not the same pickup. The difference is in the wire gauge and insulation (VHII is 42 awg plain enamel whereas the HD neck is 42.5 awg polysol), resulting in the VHII having more turns on the coil, and the magnet (VHII has the long magnet whereas the HD has the shorter magnet).
I have both pickups but have not tried them in the same guitar but I would expect the VHII to have more output than the HD neck.
Cheers Stephan
EDIT: Wow, just noticed that this was my post no. 1000.