I think when they say the vita version is identicle, they meant their won't be any features in the PS3 version that won't exist on the vita. I'm sure the graphics will be better in the PS3.
I agree with you that the PS3 will probably look better than the Vita but I think it will still look really good. The Vita has very good graphics for a handheld and it will look good on the smaller screen (compared to the PS3).
This is a question to everybody. Will you be getting the Vita version or the PS3? Or are you even sure if you are getting it at all? I will definitely be pre-ordering the Vita version.