disk image vs NDIF disk image

I am not 100% sure, I believe "NDIF disk image" is referring to System 9 (Classic) disk image, whereas the plain "disk image" nowadays is referrng to the OS X disk image.

NDIF is an acronym for New Disk Image Format

This is from an Apple Support Page dated July 23, 1997

"All future software releases will be packaged using a new disk image call New Disk Image Format (NDIF).

Apple will only support Disk Copy 6.1 (or later) or Disk Image Mounter 2.1 (or later) to access NDIF images and only support Disk Copy 6.1 (or later) to create NDIF disk images."

iDvd 5.0.1 and other applications still generate disk images in the NDIF format, it is supposed to be better compressed and a self checking format.

Hope this answers your question

Pazuita

While looking for more answers to the same question, I came across this info from The Support Site.

"What's the difference between .img and .dmg disk images?

They are similar, and you can use either with Mac OS X. One difference is .dmg disk images can be formatted in one of these formats: Mac OS Extended (HFS Plus), Mac OS Extended Journaled, Mac OS Standard (HFS), UFS, or MS-D0S. While .img disk images can be formatted as: Mac OS Extended (HFS Plus), Mac OS Standard (HFS), MS-DOS, ProDOS, or Universal Disk Format."