Look at the following conversation:
Luke: Ben! Why didn't you tell me? You told me that Darth Vader betrayed and murdered my father.
Obi-Wan: Your father... was seduced by the Dark Side of the Force. He ceased to be the Jedi Anakin Skywalker and "became" Darth Vader. When that happened, the good man who was your father was destroyed. So, what I told you was true... from a certain point of view.
Luke: A certain point of view? From another certain point of view, it could be a blatant lie.
I am confused about how 'from a certain point of view' is being used above. How is it that one point of view makes one thing true and another makes it a lie? I understand point of view to mean as viewing something from a vantage point. But, I fail to understand what that vantage point is in the above context. Please shed some light on this usage.