__________________________________________
By your definition Great Neck is a Jewish Ghetto and Manhasset is an Irish Ghetto. Of course that's not the case. An ethnic or economic or religious specific neighborhood is a ghetto only if outside forces create the isolation through some form of pressure, like with the Warsaw Ghetto.
Its all relative. A friend of mine raised in Palos Verdes, CA would definately refer to say Bay Ridge, Sunset Park, and Flushing as being "ghetto," while others would not go that far.