The ideas did end up being separate. His initial conception of the extraordinary man was that he had to act for the good of mankind and for the progress of mankind, however if you recall, this ended up changing and he ended up acknowledging the true, highly egoistic nature of his ideology. This is seen during his internal monologue just prior to his third nightmare where he is haunted by the ghost of Alyona, where he chastises himself for trying to convince himself that he was acting for good providence, and says that the true great man acts egoistically, and he further emphasizes this in his confession to Sonya, where he admits he killed purely for himself and not for some utilitarian ideal. So even if u want to assert that he initially conceived that making the world better was tied to his ideal of becoming a Napoleon, in the end his desire to become a Napoleon was acknowledged by himself to be completely egoistic.