Suonymona said:Caroline of Monaco is styled HRH of Hanover because Royal Highnesses are greater in rank than Serene Highesses. However, the German Royalty is not recognized--just called as such for courtesy so her recognized/legal title still is Her Serene Highness Princess Caroline of Monaco though she is referred to as Her Royal Highness Caroline of Hanover in almost everything...right down to her stationery.
Caroline is styled "HRH Princess Caroline, Princess of Hanover". She holds superior rank and precedence to her husband, although his style as HRH is greater than HSH, because she is crown princess of Monaco. Ernst-August is former royalty in the German Republic and his British styles are not recognized by the Crown.