What is the difference between the Byzantine empire and the empire of Charlemagne?

We are talking about the beginning of the 9th century, the differences were as follows:

Byzantium was an “old empire”, which in those years had already passed the path of its maximum power (VI century). Its territory was shrinking. Charlemagne’s empire was young, expanding in the east and south.
The empire of Charlemagne was created by 800 on the site of barbarian kingdoms (Lombards) and barbarian territories (Saxons, cheer and other tribes). Byzantium emerged on the site of the former Roman Empire, from which it inherited its culture and infrastructure. And even the names “Romans”, that is, “Romans”.
Charlemagne was emperor for only 14 years, received the crown from the Pope, and the Byzantine emperors had it continuously since 395.
In Byzantium there was a system of fems, and in the empire of Charlemagne, there were dukes.
Soon after the death of Charlemagne (843), his empire was divided into three parts, and Byzantium continued to exist until 1204, when its capital was not ravaged by the Crusaders.
Form of power: Charles has a dominate, and Byzantium has an absolute monarchy.