This is what Wikpedia states (yeah...I dislike Wikpedia too):
By contrast, allied nations such the U.S., UK and Canada, tried to treat Axis prisoners strictly in accordance with the Geneva Conventions. This sometimes created conditions for POWs better than those their fellow soldiers enjoyed at home. The lower rank prisoners were used for work on farms and road maintenance and were compensated for their work as required by the Geneva Convention. In addition, as word spread among the enemy about the conditions of Allied POW camps, it encouraged surrenders, which helped further Allied military goals. It may have raised morale among the Allied personnel when the usefulness of this approach was accepted by reinforcing the idea that this humane treatment of prisoners showed that their side was morally superior to the enemy. At the end of the war in Europe, the allied nations were not able to treat all prisoners in accordance with the Geneva Conventions. As in ancient times, German prisoners were used as slave labourers for an uncertain time and sent like chattels from one custody power to another to rebuild Europe.
In the Pacific War, Japan did not follow the Third Geneva Convention. American, Australian, British, Canadian and Dutch prisoners of war held by the Japanese armed forces were subject to brutal treatment, including forced labour, medical experimentation, starvation rations, and poor medical treatment. No access was provided to the International Red Cross. This treatment resulted in the very high death rate of 37% in Japanese prisoner of war camps. Escapes were almost impossible because of the difficulty of white men hiding in Asiatic societies.
In this event, I overstated the death rate in German POW camps, and slightly understated the Japanese brutality by 2%. But the difference between the two is much broader.