1、human強調“人群”，human being強調“個人”。
Its rate of growth was fast — much more like that of an ape than that of a human.
它的發育速度很快——更像猿，而不像人。
Each human being has to die, but mankind goes on world without end.
每個人都會死，但人類卻永無止境。
2、在壹些慣用的表達，兩者不能互換。
例如疾病的“人傳人”叫human to human transmission，但不可以說human being to human being transmission。
3、human可以做形容詞，human being不可以。
human作為形容詞意思是人的;有人性的;顯示人類特有弱點的;人本性的。
The computer doesn't mimic human thought; it reaches the same ends by different means.
計算機並沒有模仿人的思維，而是通過不同的手段達到了相同的目的。