The Japanese ordinary seaman's life was much more rigorous and the amenities far less hospitable. Very few Japanese ships had air-conditioning (I believe only the Musashi) and the tropical climate was brutal. Japanese discipline was incredibly harsh and corporal punishment was the institutionalized norm.

By contrast, American ships had such services as a gedunk bar which would serve treats like ice cream. Although discipline at the heads of petty officers could be quite severe, the type of beatings that were normal in Japanese ships could lead to a court martial.

If you really want to know more, I suggest reading Ronald Spector's At War at Sea: Sailors and Naval Combat in the Twentieth Century which has entire chapters devoted to answering your question.