This is useful information on Nikkor’s naming system:
ED = glass coating, just a marketing ploy really.
N = a better glass coating
IF = Internally focused. Focus is handled by the internal elements of the lens, and not the front element.
DX = Useful bit of information telling you the lens will only work on APS-C cameras and if used on Full Frame cameras will limit your resolution quite a lot.
via What is a Nikon ED DX Lens? – The Photo Forum – Photography Discussion Forum.