It's always struck me that Camilla was much more the royal consort type, and Diana was much more the royal mistress, like her great-grandmother Alice Keppel (mistress to Charles's great-great grandfather Edward VII).

It also strikes me there's a peculiarly nasty tone about some of the posts in this thread. The lottery of royal birth is really no different from any other lottery, except the "winners" didn't have any say in whether to buy a ticket or not, and I can't really see any reason for getting hot under the collar and needlessly unpleasant about the one and not other.