Are there any differences between "understand someone" and "understand about (someone)"?

Question

This book says

understand someone并没有“理解某人”的意思，只是“懂得某人的话”之意，如：If he had spoken French I would not have understood him.（要是他说的是法语，我可就不懂他的话了。）汉语中现在常说的“理解万岁”中的“理解”可译成understand about (someone)，如：You don't understand about me.（你一点也不理解我。）这里理解的不是指所说的话，而是指一个人的心情、做法等。Her parents really understood about her situation.（她的父母亲真的理解她的处境。）

——翻译辨误(图文版)

that "understand someone" means "to know the words that someone is saying", like

If he had spoken French I would not have understood him.

and that "understand about (someone)" means "to know how (someone) feels, behaves and etc.", like

You don't understand about me.

Her parents really understood about her situation.

But I find many dictionaries say that "understand someone" can mean "to know someone's character, how they feel and why they behave in the way they do", like

He doesn't understand women at all.

My parents just don’t understand me.

and that "understand about something" means "to know or realize how or why something happens, how it works or why it is important", like

Doctors still don't understand much about the disease.

So are there any differences between "understand me" and "understand about me"?

Answer 1

The difference is in the scope of the understanding; whereas, "understanding someone" does not specify any given aspect or a domain of the human sphere on which this understanding might bear, "understanding about someone" implies a restriction on those levels: the locutor is not concerned about understanding as a whole. This can be elicited from instances of current usage; however, the two constructions can be used to say the same thing in some cases.

• 1 And what do you not understand about him?” “For one thing, he carries a gun, which I don't like or understand. Next, he had two f1ghts yesterday with Cowboy, which you and Mother seemed to approve of and which I do not.

• 2 There were so many things she didn't understand about him.

• 3 I'm in love with Ed, but there's a lot I don't understand about him...”
  (One could have said "I don't understand him a lot".)

• 4 With this wisdom we can understand about Him, about our Father, about what His Power is like. We can know more about His Power.
  (Note that the concern is to understand more, to know more, not to know wholly.)

• 5 There is a level, a deeper level that God wants us to understand about Him.

• 6 One way is to understand about him . I read about him , I hear others talk about him , I hear him discussed at staff conferences – I understand about him . I understand him , so to speak , through the eyes of others , not through my own or his.
  (Finally, understanding about him becomes "understanding him", which is nothing more than a generalizing statement.)

• 7 But there is something I don't quite understand about him. Something enigmatic, as if he is operating behind a mask.” “That's because he's an Arab,” said Hoffman. “These people are born with masks on.”
  (Note that "don't understand something … about him" is more specific than "I don't understand him", which would be an overstatement once the locutor reveals it is question of nothing else but the character's attitude.)

• 8 But the more we understand about him, the better our chance of catching him be— comes.”
  (Here, "But the more we understand him," would have done as well since the state of understanding is made partial by the adverb "more".)

• 9 He expects me to do penance for things I will never begin to know or understand about him.