know of 跟konw about 有什么区别？

know of
了解的不深，表示知道一点或者听说过，只知道有这么回事
know about
非常了解

两者是程度的不同而已
一楼的例子就不错

I know of him.
我听说过他。
I know little of their history.
他们的历史我知道得很少

Does she know about it?
她知道这件事吗？
You know much about it.
看你对它了解得挺多的。

你比较，体会一下

I know of him.
我听说过他。
I know little of their history.
他们的历史我知道得很少

Does she know about it?
她知道这件事吗？
You know much about it.
看你对它了解得挺多的。

know of
知道有...
know about
知道..., 了解..., 听说过...