Nellie, I was being oh-so-correct, as I have always learnt it on this topic.

King Edward's Chair is a chair. As you know, King Edward I ordered it built to house the Stone of Scone. It is a chair and not a throne. It is also NOT St Edward's Chair. St Edward was the Confessor and St Edward's Crown (in its original form) was his crown.

The chair on the South side of the Theatre is a Chair of Estate. The Sovereign sits in it until his election has been confirmed through the Recognition and he has sworn the Oath. Hence also the Parliament robe at this stage in the Rite because he is deemed first amongst equals until the Archbishop has satisfied himself that he's got the right man.

The chair on the dais is a Throne-Chair. It serves as a throne because the anointed and crowned Sovereign sits in it.

This goes for the multiplicity of Throne-Chairs that exist.

The ONE and ONLY Throne is in the House of Lords. This is where the Sovereign sits with Parliament assembled before him, the Cloth of Estate behind him. He rules from this Throne, tells Parliament what they are to do in their next Session and gives the Royal Assent.