The opposite of a hardcover book would be a " softcover" (softcover) book.

与书相反的是“软皮”（softcover）书。

Softcover books are usually cheaper, lighter, and smaller than hardcover books.

书常比书更便宜、更轻、更。

Both hardcover and softcover books are divided into two categories or types: fiction and nonfiction.

书和平书都分为两类或类型：说类和非说类。