I think that there are some significant differences in the manner in which Kurtz is shown in Coppola's film and Conrad's book. One difference is that Kurtz dies on the journey back in the book, while in the film, Kurtz does not leave his compound upon Willard's arrival. At the same time, Kurtz seems to die of modern causes in the book, while he is clearly killed in Coppola's film at the hands of Willard. Another change would be the level of brutality that Kurtz displays in the film. While the book shows him to be violent, the film shows this to another level. Both depictions are savage, but I think that the film shows it to a far greater level. Finally, I think that Kurtz is shown as sick and ill in the book, while in the film this dimension is not as explored.