Someone once explained the difference between The Princess of Wales and Diana, Princess of Wales. The first one is a title. Being an American, it is very different from what we are accustomed to. The title is used in passports, it is part of your designation. It appears on all official documents. The second one is used as part of a person's name.
I see where you're coming here, but you're a bit of base. All titles are essentially names, that's why they can be used in passports.
An untitled man would be Mr. John Smith. His wife would be Mrs. John Smith. Were they to divorce then she would become Mrs. Jane Smith; prior to her marriage she would have been Miss Jane Doe.
If you give John a title, however, he becomes The Duke of Wherever, and she becomes the Duchess of Wherever. Her title remains the female equivalent of his, without any of her own name, so long as they remain married. If they divorce, however, she becomes Jane Smith, Duchess of Wherever, until she remarries.
The same thing happened with Diana. When she was unmarried she was Lady Diana Spencer - Lady in place of Miss. When she married Charles she took the feminine equivalent of what essentially is his name, The Princess of Wales. When they divorced, she inserted her name into the mix - Diana, Princess of Wales. All the Queen did was take away the styling entitled to her as a member of the royal family.
Diana actually did not hold any titles herself.
Diana didn't hold any substantial titles, but she did hold courtesy titles. Lady is a courtesy title, as is Princess of Wales when they're held by the means as Diana held them (as a daughter or a wife).
Styling is something different altogether. While she was married Diana's title was Princess of Wales, her style was HRH. When she divorced she didn't lose any titles - it was just changed - but the Queen stripped her of her style (although, I guess she could have gone back to