Master, Who Is the Substitute for Whom?

I am Jiang Huaiqing. Senior brother, he saves lives and heals the wounded. He is an irreplaceable hero in my heart. But why is my second disciple Wei Huan, who will become a demon in the future, always compared with his senior brother? But Wei Huan does look a lot like him... I probably didn't confuse them! Wei Huan is Wei Huan, and senior brother is senior brother. Who is whose substitute...