There is
way more to a game engine than graphics. And there are too many factors to take into account, so no vote from me.
How it looks depends a great deal on how good the artists, how detailed the textures are are how many effects are used, the hardware it's running on and so on rather than the engine. I mean, the Unreal 3 engine is behind both http://www.youtube.com/watch?v=0QIBaKX_RkU and http://www.youtube.com/watch?v=RSXyztq_0uM, but one of the videos look noticeably better. Not to mention that the looks of Oblivion been greatly enhanced thanks to various mods, but it's still the same engine.
The biggest difference between the Creation Engine and most other game engines is that the Creation engine is pretty much coded for a general case. The other engines are pretty much "special purpose" engines. The areas are all pre-calculated and optimized, few things (if any) ever changes in them, etc. Whereas Creation Engine is coded for the general case. Basically, Creation Engine is sort of like Microsoft Word, and the master esm file is a document. The program has to handle the general case for everything -- terrain, buildings, statics, items, NPC's, etc. But an Unreal 3 engine game can have specific code to handle specific areas, they can pre-calculate lighting (even with weather & time of day changes), they can optimize paths and collision, etc. This makes the Creation Engine slightly slower than the competition, but I think it's a perfectly valid trade-off, going with better and easier to develop content over render speed. It makes it easier for the developers to make a huge explorable game world filled with interactive clutter and it also proved to be a very GOOD thing for the TES modding community for the past 2 games.
If Betheda had started to work on Skyrim with the Unreal 3 engine, I'm sure it would still be years from being completed, the game would require multiple discs (the esp plug-ins is a very efficient way to store game world data) and have longer loading times. But I there would have been a slightly higher framerate.
It wouldn't really have looked any different though, cause there would have been the same artists working on the game anyway, and they would have made the game for the current consoles anyway and everything wouldn't be able to be in great detail cause it's a large open game so a lot of things will have "medium" quality instead of a few things having "high" quality. The smaller the game, the more detailed it is. Just compare a character from GTAIV to a character in Soul Calibur IV or something (they were both released the same year), the Soul Calibur IV characters look noticeably better and more detailed. There is really no way Skyrim will look better on the PS3 compared to a linear level based game on the same platform, such as Uncharted. The focuses of the games are simply too different.
Rage Engine:
http://www.youtube.com/watch?v=pROWml_4sYQ
IDtech 5
http://www.youtube.com/watch?v=b4ieFw2s7Fw&feature=related
They are the same thing.