Why was Frederick I only called "King of Denmark" while Christian III was named "King of Denmark and Norway"?
Frederick I of Denmark Frederick I (7 October 1471 – 10 April 1533) was the King of Denmark and Norway. His name is also spelled "Friedrich" in German, "Frederik" in Danish and Norwegian and "Fredrik" in Swedish. He was the penultimate Roman Catholic monarch to reign over Denmark, when subsequent monarchs embraced Lutheranism after the Protestant Reformation. As King of Norway, Frederick is most remarkable in never having visited the country and was never being crowned King of Norway. Therefore he was styled "King of Denmark, the Vends and the Goths, elected King of Norway".
Frederick V of Denmark Frederick V (Danish and Norwegian: "Frederik"; 31 March 172314 January 1766) was king of Denmark-Norway and Duke of Schleswig-Holstein from 1746 until his death. He was the son of Christian VI of Denmark and Sophia Magdalene of Brandenburg-Kulmbach.