1. Though Moses also saw images and likewise knew that they weren’t of G-d Himself like the other prophets, his level of prophecy was still and all of an entirely different and more sublime order than theirs. We’d cited this before, but Ramchal is most explicit about it here.
The other prophets “weren’t able to fully look upon the images they saw”, they could only glance at it or scan it quickly, and never in depth, as he indicates. That’s because they were looking as if from “behind a wall” or through “several lenses”. As such, their visions “lacked clarity”. But Moses’ vision was far, far clearer.
As some sages put it, “while the other prophets saw (what they did) through nine lenses, Moses saw through one”; and as others said, “while the other prophets saw (what they did) through stained lenses, Moses saw through a clear glass” (Vayikra Rabbah 1:14). It’s as if the other prophets saw something after having rubbed their eyes hard in wonderment, which smudged the image, while Moses saw what he did after having stared in stark amazement which only slightly compromised the image.
Those other prophets couldn’t quite make out what they were looking at and couldn’t quite grasp it thoroughly. As such, even their understandings of its import were affected. One really couldn’t have expected otherwise, though, as Ramchal makes the point, since”the images they were granted were only meant to express general notions” rather than specific injunctions or the like. (Compare, for example, Ezekiel’s inexact warnings about the idol-worshipping that was going on in his time with Moses’ specific prohibitions against idol-worshipping, and the like.) So they had a somewhat vague idea of what they were being told.
Moses, on the other hand, had a clear, crisp understanding — “as clear as any created entity could have”. And he thus attained the very highest degree of communication from G-d.
2. Here’s another way Ramchal proposes we look at it. We’re not suggesting that the prophets merely saw things with their eyes (which would mean, of course, that their visions would be affected by their being long- or short-sighted, and that would be what would set one against the other).
They experienced “spiritual visions”, as Ramchal terms it, that didn’t depend on either their own physical conditions or on their surroundings. And since each of them was unique, each prophet had a unique spiritual vantage point from which to see.
Now, a spiritual vision would allow one to “see into” all sorts of things he wouldn’t ordinarily be able to. “One could ‘see’ what lies inside a barrel”, for example, “or see through a wall” thanks to prophetic vision, which he could never do otherwise, Ramchal remarks. That explains the variations of their visions, and how one of them was able to “see” the image of a lion or an eagle when there wasn’t one actually there at the time (see Ezekiel 10:14). The point is that if the other prophets were able to see such wondrous things thanks to their spiritual visions despite their limited scope, one could only imagine the depth of perception that Moses’ images and messages entailed!
Rabbi Yaakov Feldman has translated and commented upon “The Gates of Repentance”, “The Path of the Just”, and “The Duties of the Heart” (Jason Aronson Publishers). His works are available in bookstores and in various locations on the Web.