What's the difference between a book and a novel?
It's a bit like the difference between clothes and trousers, all trousers are clothes, but not all clothes are trousers. So - all novels are books, but not all books are novels.
A novel is a book. A novel is a type of book that tells stories. It is a book of long narratives. Novels have different genres. There are action novels, romantic novels and sci-fi novels.