No difference if glass, coatings, build quality, or reliability. The new elevation turret is the rising style with the second rev numbers visible on the second rev, instead of the older pin extrusion to indicate you are on the second rev. 4X's are a great deal right now, but as noted, they are getting hard to find. The 56 will be a little brighter at dusk and dawn, if that is worth it to you. The 3-12x56 was originally designed as a super bright, super clear scope, in daylight hours, I doubt you will be able to tell the difference.