1、意思
him的意思是他。
例句：Johns aunt died suddenly and left him a surprisingly large sum。约翰的婶婶突然去世了，留给他一笔巨额财产。
his的意思是他的。
例句：Brian splashed water on his face, then brushed his teeth。布赖恩用水冲了把脸，然后刷牙。
2、词性不同
him是第三人称he的宾格。
his则是形容词性物主代词。
3、用法不同
him在句中作宾语，放在动词或介词之后。
例句：I was chatting to him the other day。前几天我和他聊了一阵。
his在句子中作物主代词，后接名词。
例句：He spent a large part of his career in Hollywood。他的职业生涯中有很长一段时间是在好莱坞度过的。