Exactly - there are specific coronets for the heir apparent, his (and now her) children, other children of a sovereign, and grandchildren of a sovereign - peers or not. Potential royal coronet wearers for Charles's coronation would be William, George and Charlotte (depending on their ages), Harry, Andrew, Beatrice, Eugenie, Anne, Peter, Zara, Louise, James, Edward, Dukes of Gloucester and Kent (if he's still alive, if not, his son will as an "ordinary" duke) Prince Michael, and Princess Alexandra - assuming the Queen's cousins are still alive of course. I'm not sure, but I believe that Catherine, Sophie, Birgitte, Katharine Kent and Marie-Christine would also be entitled as wives, as would the future Princess Harry.