On occasion, the women have represented the family together.
Body language expert Judi James analysed their interactions for Express.co.uk.
In 2008, just a few years after Camilla took on her royal role, the women attended the Order of The Garter Service.
Although they were standing close together, Judi claimed their body language showed a distance.
“Together but also apart again,” the expert observed.
“Camilla and Sophie stand side-by-side here at Ascot but with a large spatial gap and what appears to be no attempt to socialise or share the moment.”
The body language of the royals does not show signs they are trying to connect, the expert claimed.
“Both are smiling but their smiles are not ‘pinging’ smiles of shared humour or fun,” Judi suggested.
“Both hold their bags clutched in front of their torsos in a barrier gesture.”
This is not the first time Sophie and Camilla have displayed this type of body language.
Judi highlighted a trip to Trooping the Colour where the royals shared a carriage for the royal procession.
She suggested that, although physically close, again they did not display any public signs of closeness.
“Riding together in the carriage Camilla and Sophie look like two women who might be close in terms of proximity but distant in terms of a lack of engagement,” Judi continued.
“Their non-verbal signals could hardly be more contrasting.”
Instead of focusing on Camilla, the expert alleged Sophie gave a lot of attention to royal fans.
“Sophie is looking hugely sociable here,” the expert added.
“She was beaming at the crowds with one hand raised in a ‘hail’ wave, with the palm flattened to signal a very friendly approach.
“Camilla, however, sits with her hands on her lap, looking out at the crowds with what looks like a more gloomy facial expression.”