I think the difference is that these were taken by a fashion photographer, who I assume is more used to taking photos of models rather than portraits to capture the real person - or paparazzi pics.
I agree.
And even if this is the ‘real Catherine’, it’s odd to present something that is do visually different to the version of the Duchess of Cambridge you see presenting the Wimbledon trophy/ attending premiers/ doing activities with the Scouts/ on Holkham beach as a Royal Portrait.
Obviously she is perfectly entitled to change her hair and makeup, but I think it’s the angles and lighting that make her look unlike herself.