The young royals are both dressed smartly in blazers and trousers, paired with open-collared shirts, and even strike similar poses with their hands clasped.
Although Queen Mary, 52, did not take the official photos of her son Christian, she is known for sharing her own personal snapshots of her family.
Previous birthday portraits of George have been less formal, such as when he was seen smiling in an England shirt for his sixth birthday in 2019.
However, both he and Crown Prince Christian have comparable futures, as they are destined to become Kings of their respective countries.