First of all, we know that Guan Yu is loyal to Liu Bei. Guan Yu won't be moved even if Cao Cao has a high official and a beautiful BMW to send him. Such a person will not change easily once he finds his master, so if Cao Cao Can influences him, Guan Yu will be loyal to Cao Cao to the death. But Lu Bu is different. We know that Lu Bu is a domestic slave and has three surnames. Anyone who makes a little profit for him will benefit. Even if such a person is subdued, it is equivalent to raising a tiger.
Secondly, he sticks to his own heart and is unmoved by the temptation of the outside world, such as Cao Cao's kindness to him. This kind of tolerance is just different. Someone who can achieve great things at a glance. But Lu Bu is different. You give him a little benefit, or give him a beautiful woman, and he becomes fascinated. Will leaders use people like Lu Bu?
Finally, the value of Guan Yu's force. Guan Yu was one of the five Iliad generals. He killed Hua Xiong with warm wine, Yan Liang and Wen Chou, and he was even more powerful among the armies, and he was heroic and furious. In fact, the force value of the ruble is also good. In my opinion, it's even better than Guan Yu, because there is a plot of three English wars against Lu Bu, and Liu Bei, Guan Yu and Zhang Fei beat Lu Bu back. But Lu Bu can't be clever. Close design to catch the enemy, lyu3 bu4 only brute force. We said that if you can use your brain, you don't have to do it.
In contrast, Guan Yu is much superior to Lu Bu. This is why Cao Cao liked Guan Yu but killed Lu Bu.