In terms of tonnage, not dollar value. In terms of dollar value, Korean order book was three times bigger than Chinese order book.China was way behind many countries in shipbuilding just a decade ago and last year became the top shipbuilder in the world
Basically what's happening is that 90% of Korean orders are for high value ships(oil rigs, LPG tankers, etc) from European and US shippers, so Korean business is heavily dependent on European and American economy.
In case of China, it is the reverse and the majority of orders are from Chinese shippers for cheap bulk cargo ships; these have very low dollar value per ton, so the size of Chinese shipyard's order book is directly tied to Chinese economy.