By the look at it, obviously the color white balance is way off for both pictures. You can judge by your wife's arm color.

There is however a slight difference on the material type. The left photo looks more like a shinny material. More like Satin or Taffeta. And the right photo doesn't look shinny. Again its also maybe of the lighting of the venue. Whether is it shinning directly to the dress or how.

But you do have a point on the edge and the pattern. Slight difference between both photos.

Could it be the staffs from the bridal house have also mixed up the gown themselves. And knowing the hassle, just insist that its the correct one. Maybe you should try bringing up the issue to the boss or someone in charge. Usually the workers would not bother very much.

Cheers and hope it all works out.....