I ask this because I learnt that when the Queen is in England, she’s the head of the C of E. When she’s in Scotland, she’s head of the C of S. How is this possible if the two don’t believe in exactly the same thing?
I also know that one member of the Royal family (I think it was Princess Margaret) had her second marriage in the Church of Scotland because they’re more lenient on remarriages for divorcees. Thus I’m imagining that this means their beliefs aren’t identical.
The Queen is Supreme Governor of the CofE (not “Head”) but she does not have that relationship with the CofS. She does attend CofS services when she is in Scotland.
The CofS is Presbyterian, the CofE is, well, Anglican. It is not unusual for Christians of one denomination to attend services in churches of another denomination. Certainly I have seen senior Catholic prelates at Anglican services, the wedding of the Duke and Duchess of Cambridge among them.
They’re not identical, but are broadly similar. Historically they were even more so: the Church of England used to be more Calvinist in its theology, and the Church of Scotland used to have bishops. Both the loss of Scotland’s bishops, and the constitutional settlement which sees the monarch as a member of both national churches, has a lot to do with the fact that William III (of Orange) was a Dutch Calvinist.
As others have said, the Queen is the supreme governor of the Church of England.
When she is in Scotland, she is just a member of the Church of Scotland. However, as Scotland’s national church, the Church of Scotland does participate in royal traditions. For example, upon their coronation, monarchs pledge to defend the security of the Kirk. She also appoints a Lord High Commissioner to personally represent her at each of the General Assemblies of the Kirk. The post of Lord High Commissioner is purely ceremonial–they have no authority in the church at all.