What is the difference between a textbook writer and a curriculum developer?

I would say that a Textbook writer is someone who writes the textbooks...maybe a person who can type well that copies what someone wants in the books for the final copy ready for print. They might not have a lot of knowledge of a certain subject but they can type fast and accurately. A Curriculum Developer on the other hand is the brains behind the book. They are the one who decided what is going into each book that is created. I am sure that their job would be very time-consuming and much more difficult that the writers job.