http://www.nikonchat.com/nikon-nikkor-lenses/
Nikon Nikkor: Is there a difference between "D" and "G" series?
Currently I am buying Nikon lenses and I'm not sure whether the difference in the names of all means so much.
D = the lens has an electronic chip in it, the remote communication of information the lens of the camera, which is often used for things like flash metering. G = A D-type lenses (has the D-chip), but no aperture ring on the lens. The opening must be set to the camera. The first G lenses were also indicative of a lower quality lens with plastic mount, but this is not true because that practically all the latest Nikon no aperture ring and "G" lenses.
nikon nikkor 50mm F1.4D Lens unboxing
Nikon News