Forty three images in the Phantasy Star III Scenes and Stills galleries have been replaced with new versions of the images. The new versions have brighter, more vivid colors than the older images.
The replaced images include all of the speaking and status screen portraits, all but two of the cutscenes, Azura, Dahlia, the shuttle, and the two top-down views of worldships. Since the majority of the Phantasy Star III avatars in the avatar gallery were speaking portraits, this also means many of the avatars have been updated with these new versions.
On a more technical note, all of the new images are .png instead of .gif, meaning they are smaller files as well as better quality.