One of the greatest benefits of Scrivener is its ability to help manage sections of a book-length document. You can quite literally select a section of your book, and then drag it and drop it to another part of your book without any fuss.
Scrivener’s Binder (the left pane in Scrivener) also allows you to see at a glance which sections you’ve written, which can then help you to do determine which sections you may still need to write.
But not everyone is comfortable with Scrivener at first. Things may not be where you expect them to be (though this downloadable cheat sheet can help you get your feet under you). If you prefer to stick with the devil you know, then there’s a way to “hack Word” and get it to behave like Scrivener.
More here - How to Make Word Behave Like Scrivener