The question is asking us to describe a difference in the rule of emperors Diocletian and Constantine. Diocletian was a Roman emperor from 284 to 305. He created Tetrarchy ( " the rule of four " ). he divided Roman Empire into the Eastern and the Western Empire, ruled by 2 Augustus and 2 Ceasars. He appointed a co-emperor to run the West with him. Constantine the Great was a Roman emperor from 306 to 337. He was a firs Roman empire who supported Christianity. He reunited the Empire under one emperor. Answer: Diocletian divided and Constantin reunited the Roman Empire.