Robert Lacey, a royal expert and historical consultant for Netflix's The Crown, tells PEOPLE, 'There has always been a special closeness between William and the Queen, and she has taken a particular interest in him.'
'When William became a teenager, she would have him at Windsor Castle and would open the state boxes and guide him through the papers. It was William’s constitutional education,' Lacey added.
While William has been training to become King since his childhood, it's quite a different story for wife Catherine, Duchess of Cambridge.
As the wife to the reigning monarch, Kate will become what's known as the Queen Consort.
The world will know the new Queen as Queen Catherine, according to expert and author of blog Royal Musing Marlene Koenig.
'Unless decided otherwise, a Queen consort is crowned with the King, in a similar but simpler ceremony,' the official coronation page on the royal family's website explains how Duchess Kate will likely be crowned.
But the site also shares a key difference between the wives of Kings and the husbands of Queens: 'If the new Sovereign is a Queen, her consort is not crowned or anointed at the coronation ceremony.'
Koenig also reveals that should Kate outlive William, she could adopt the title of Queen Mother.
'When [Prince] George is King (if Catherine is still alive), she can choose to be styled as HM Queen Catherine, the Queen Mother,' Koenig says.
The last time England had a Queen Catherine was under the reign of Charles II. A Portuguese princess before she married Charles, Catherine of Braganza was Queen consort from 1662 to 1685.
This article originally appeared on New Idea.