Blade Runner differences between text & film

There are so many differences between the novel “Do Androids Dream of Electric Sheep?” and the film version in Blade Runner. The text include the topics from humanity, relationships, technology and religion to environment, and animal extinction, but the film version focuses primarily on artificiality, romance, relationships and mortality.
The opening scene from the text starts with Rick Deckard and his relationship of having a real, living animal where in the film there is no mentioning about his electric sheep whatsoever. Even though they mention a little bit about the fake owl when Rick goes inside Tyrell Corporation, it doesn’t play the important theme later on in the film. In the novel, Deckard owns the fake sheep and he wants to own a real animal so bad. Later in the story, Rick purchases a goat and this goat represents an important status symbol of his elevation of electric animal owner. The goat also represents something for Rick to redeem himself for killing androids. Because Rick buys an expensive animal, he has to keep killing androids in order to pay for it.
Another difference between the film and text version is that the film relates to humanity and mortality. For example, we can see that the relationships between Deckard and Rachael in the novel are portrayed differently than in the film. In the Film, their relationship between Rick and Rachael has no ill intentions toward each other. Deckard is being rough at first when he tells Rachael that she is an android and her memories are implanted, so nothing that she thinks is real. When Rick sees her tears, he feels empathy toward Rachael and offers to bring her a drink. She leaves without accepting it, taking her grief with her. Deckard feels slightly depressed in her absence. On the other hand, in the novel, Rachael does not care about Rick. Instead, Rachael feels empathy toward the other androids. Rachael seems very upset about Rick’s plan to kill the other androids. She even tries to delay him by promising to kill other android for him. When Rick shows his humanity by sparing Rachael’s like, she turns back into an android. where in the film doesn’t mention that at all. For the film version, I think they are trying to add romance into the story which gives the audience to feel empathy toward this android, so there is a play of emotion part in the movie.
Finally, there is no religious theme in the film. The text mentions about empathy box which is an electrical energy device that uses to stimulate feelings in its user. We also learn about Mercerism. Mercer is a man named in the empathy box that allows user to feel every sensation that Mercer does. Mercerism also plays important part in making religious decision. Rick also uses the empathy box. Mercer’s word aids Rick to force him to kill the androids.