These images were all made without that fancy new-fangled gamma correction doodad.

The dress should be exactly the same in both images since it doesn't use a texture map.
The comparison is in the color of the skin: the first image (on the left) is much more washed out than the skin-tones in the image on the left.

As some of the posters said, this style isn't meant to be super-realistic, but more of an animated/ stylish look.
For more realistic renders, I recommend using the full set of shader nodes, including sub-surface-scattering, translucency, ambient occulsion, and HDRI lights... and of course, a more realistic background than plain white.

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