"The true enormity of what his life will one day be isn't something he's fully aware of yet," she added.
"I think George understands, like William did from a very early age, that he's different from his younger brother and sister and that he'll have a different future.
"After all, he gets taken away to do photoshoots with Her Majesty the Queen, so he must notice he's been singled out."
The Queen's Christmas Day message included footage of George making Christmas puddings with his father, grandfather and great-grandmother.
But his siblings weren't included in the clip, while George was also photographed in a portrait with the Queen and her son and grandson, released in January 2020.
Nicholl also said that William and Kate, who have been with their children at their Norfolk residence Anmer Hall during lockdown, want them to feel equal.
And though George is third in line to the throne, they're not spoiling him or giving him special treatment.
It's a far cry from how differently William and Harry were treated growing up, the royal author claims.
She said that when the brothers went for tea with the Queen Mother, William would be given first choice of the selection on offer.
William is also said to have struggled with the realisation that he "had no choice about which path his life would take" and he doesn't want George to be affected by the same worries.
