Okinawa was bloodier in the fact that more men died. However, the bloodiest battle could be based on more than just casualties. More men died on Iwo Jima per square mile than they did on Okinawa. In addition Iwo Jima was much more savager than Okinawa. Remember, the Japanese classified Iwo Jima as part of japan and they weren't going to let it go without a major fight, more so than any other island. In that sense Iwo Jima could be classified as the bloodiest battle in the Pacific.