His Name
You seem to be confident that the Prince of Wales will one day ascend to the throne. That is a question to which none of us can provide an answer. [Charles and I] will continue to disagree on this topic, and it will be a source of ongoing tension in the future. Being the Prince of Wales is a challenging job that is on par with being a king in terms of difficulty.
Her Title
When Diana commented on this, it became evident that she was referring to the fact that “being the Prince of Wales allows greater independence, but being the King may be extremely constraining.” I understand that he would be unable to accept the responsibilities.