Is the original hard harder than arrange? Original has more zombies, no auto aim, fewer ink ribbons but has extra items like the green herb outside the police station entrance. Talking about this specific pc version, is original the usa/international version and arrange the japanese version?

I would say Arrange Hard is more difficult than Original Hard, because while there might be less enemies there's also less resources. At least that I could find. This is a much bigger issue with Claire and her projectile based weapon, the 'Nade Launcher. The challenge could be lessened considerably by taking the S. Machine Gun from the armory locker while playing as her. However, I usually leave the contents of the locker for the Bee/2nd Scenario.