The fullscreen version appears to be better than the widescreen version since the original negative size is closer to 1.33 than to the widescreen aspect ratio (similar to James Cameron's Aliens). The widescreen release had the top and bottom part of the image covered to make the screen size fit.
from DVDTown:
Alas, things are still never so simple, because the new full-screen edition they give us is, in fact, not a true pan-and-scan rendering of the film at all; that is, Warners did not take a portion of the widescreen image and blow it up to fill the entire 1.33:1 area of a television screen. After comparing a dozen or more scenes in the new full-screen edition to the exact spots on the new widescreen edition, I found the new full-frame version to have cut off only a fraction more image information left or right, while providing more information top and bottom. The new full-screen edition would appear to be closer in size to the original film frame stock from which the widescreen was matted, although, interestingly, there are size differences between this new full-screen and Warners’ old standard cut of the film. (d**n, isn’t anything easy?) What’s best, though, is that the colors in the new editions are cleaner, sharper, brighter, richer, deeper, and better defined than on the old editions, ostensibly the result of new transfers or better production techniques.
