I'm a little puzzled because unless I'm mistaken it seems the screenshots shown on the product page for RoA 3 are exactly the same as the ones for RoA 1+2. Is there really no difference in the graphics? I'm just curious. Thanks.

the dialogue boxes are a bit better, the combat graphics are a bit neater too, the fps view is a lot better ihmo.
i think to remember that there were also a lot more videos and rendered effects, that's why it's a lot bigger than the other two.
but overall it's pretty much the same just a bit more polished.
EDIT: the resolutions seems to be higher too, or at least it isn't so pixellated.

Here is a video of the game play for the game to give you a better idea of what things look like.
Realms of Arkania - Shadows Over Riva