How are Ansem and Ansem the Wise different?

Ansem the Wise, is the original Ansem, in KH 1 the Ansem they go by is a heartless, with the replica of his understudy, who is the same as Xeanhort from KH 2, Ansem the Wise is the Ansem that made the Ansem reports. Ansem the Wise is the body of Ansem Heartless (KH 1), Xeanhort is the nobody of that heartless, and he is Terra from Birth by Sleep, who was infused heart and soul with Master Xeanhort, the old man from the trailer. Sorry for the spoiler. Terra and Master Xeanhort were fused and that is why he is younger than Master Xeanhort, nd hwy he looks like Terra.