zlacker

It's the property of the Crown, which is legally a corporation sole with the monarch as the sole 'member' of the corporation. It means, for example, that Charles gets Buckingham Palace and the crown jewels automatically by operation of law on becoming king, rather than via Elizabeth's will. A similar arrangement applies to Anglican vicars who have the freehold of their church - it's owned by 'The Vicar of Bray' rather than by Rev Smith.

It's generally understood by constitutional scholars that the Crown is essentially governmental rather than private and the Crown Estate would go with the government rather than the royal family if the assets were split up on the creation of a republic.

The Queen also had extensive private wealth, including Balmoral Castle which (unlike the royal places) was hers personally rather than as monarch. IIRC it was bought privately by either Victoria or Albert rather than via the Crown Estate. This mattered after the abdication of Edward VIII, where the property of the Crown passed to George VI as the new king, but the private possessions of Edward stayed with him. I think Balmoral and Sandringham had to be bought off him so they would stay as royal residences. Presumably most of that private wealth will be bequeathed to Charles, though we won't find out: the Queen's will is, uniquely, private by statute.