Bo Xiao refers to the fans' love for Yi Bo and Xiao, among which Bo Jun refers to Yi Bo and Xiao En Ai. "Boshaw" means that fans like Abreu and Shawn Shaw.
Fighting for the king means that Sean Shaw is dominant in a certain field or situation. It means that Sean Shaw showed his extraordinary talent and leadership in a certain field or occasion and became a sought-after king.
So the difference between the two lies in the difference in meaning.