Your Majesty: It is the honorific title given to the emperor in ancient China, translated as "you".
Your Highness: It is the honorific title for the queen, crown prince, and kings in ancient China. The first honorific title for the emperor is "Your Majesty."
Extended information:
The original meaning of "尧" is steps. Specifically refers to the steps of the palace. "Jing Ke's Assassination of the King of Qin": "Qin Wuyang presented the map box to enter His Majesty." In ancient times, the emperor's guards were on guard on both sides of His Majesty. "Your Majesty" is the honorific title given to the emperor by his ministers. When the emperor was talking to his ministers, he did not dare to address the emperor directly. He had to first call the waiter at the foot of the steps and tell him. Therefore, calling you "Your Majesty" means conveying humble words to you through your subordinates at the foot of your steps, which means that the humble are speaking to the venerable.
The word "Your Highness" appeared in ancient books much later than "Your Majesty". Generally speaking, the honorific title "Your Highness" is used for princes, princes, empress dowagers, and empresses. For example, during the Southern and Northern Dynasties, Qiu Chi's "Reply to Chen Bo's Book" in "His Royal Highness Linchuan of the Chinese Army, Ming De Mao Qin" refers to Xiao Hong, the prince of Linchuan County. But "Your Highness" is mainly used for princes and princes. They live in palaces, hence their name.