Actually they wouldn't look any different. UE4 doesn't improve the capability of graphics for shows and movies, it allows for real-time rendering of things that previously had to be done ahead of time because of the processing requried. You know how an intro video to a game looks 100 times cooler than the actualy game? UE4 will allow the game to look just as cool. For a show or movie they could always add as much detail as they wanted because it was no big deal if it took a few minutes to render a single frame.