Slides are totally different. Any subtle difference is readily observable. From slides, now I see the subtle color rendition of different lenses. I never got prints from the same negative by difference orders that look even similar in terms of colors. In my opinion, if this type of prints is all that you've looked at, you are not qualified to talk about most of lens optics.
Slides have different visual effects as compared with prints.
For a slide, lights are filtered through it as if they were emitting from the scene. A bright spot in a slide really glows, and colors are purer and more saturated. I found that scanning from color prints is not such a good idea. None of these problems occur in scanning of slides. Several people pointed out to me that it is not fair to compare the scanned images from prints and from slides, and what I should compare is the scanned images from negatives and slides.