Both dramas have both the main male leads as brothers but both characters don't know that they are brothers. Both the father and mentor of the main character for both dramas was played by the same actors. Finally, both dramas are about avenging the death of a father, but also becoming the true king that the people of Joseon deserve.
It is always best to see how it all started! This was my first Japanese drama and I loved it! It was really cute and adorable. Also it is awesome to marathon when the second season is done...