According to my converter thing I googled, size 2 us is size 4 uk and size 8 is uk 10, pictures are deceiving due to angles,lighting etc so I refuse to judge on 2 completely different styles of pictures.
Going from the dress sizes and the likely body frames you must have to be them I'd go with you as looking better in the dress, 4 is far to skinny, I like curves on a girl, my ex was an 8 I think, your only one size up from her and I liked my ex's figure.
Many people say your friend probably because the photo you posted of her gives a lot better angle, a slight side on view showing more curvature and that's what guys find attractive. Hence why they have chosen her all the time and why I can't judge on the photo's when they are far too different poses and angles.
well you don't seem that different to me body wise,but when it comes to how you wore it,i think you did it better,her bra is showing and she isn't filling up the chest area and those tight don't really go with the dress. also,lose the attitude,you are far too bitchy for someone who asks so many questions of the same community she's bitching at.