I noticed HFNR softcover came out on March 2009. What's the difference between it and the hardcover? Any difference in terms of the content?

Also, in terms of the publishing industry, what motive does a publisher have for creating a hardcover version of the book first and then the softcover? I notice many softcovers are cheaper than hardcovers. Why is that? Shouldn't the hardcover be worth slightly more for outer protection?