正是 vs 便是?
What is the difference? What is the etimology?
As far as I know 正 should be regarded as "straight", so 正+是 (straight+true) which can be translated as "straight like" or "exactly as".

But 便 should mean something like "handy" or "being handy". By the way you can see "a handle"(top)+ "a hand"(bottom) and "a man"(left) in the character itself. So what does 便是 exactly mean and what is the difference with 正是? 便是 should have some special connotation quiet different from 正是 or at least the were different in the old times.

Yes I know the difference should be tiny. Please, refrain from stating that "they are equal".
p.s. PLEASE, guys. I'm NOT interested in how 便是 can be changed into some other 即使纵然就是 and so on. I'm interested in WHAT WAY 便是 is DIFFERENT from all other such phrases.Guys thank you for your answers, but still your examples are not enoug.
So what I can gather from your posts^
1)便是 is more formal and used mainly in literature, articles. Not interesting because It does not uncover nature of 便.
2)正是 is 100% sure while 便是 is not 100%. Not interesting because it does not uncover the nature of 便.
3)便 is more like "so" rather than "straingt" or "then" or "just". Now THIS IS interesting.!!!

If someone could read the article
https://drive.google.com/open?id=0B7f68zPex4RieXlKMzZNdV9Ndm8
then maybe we all will have interesting answers for this question. Thanks

Question

正是 vs 便是?
What is the difference? What is the etimology?
As far as I know 正 should be regarded as "straight", so 正+是 (straight+true) which can be translated as "straight like" or "exactly as".

But 便 should mean something like "handy" or "being handy". By the way you can see "a handle"(top)+ "a hand"(bottom) and "a man"(left) in the character itself. So what does 便是 exactly mean and what is the difference with 正是?  便是 should have some special connotation quiet different from 正是 or at least the were different in the old times.

Yes I know the difference should be tiny. Please, refrain from stating that "they are equal".
p.s. PLEASE, guys. I'm NOT interested in how 便是 can be changed into some other 即使纵然就是 and so on. I'm interested in WHAT WAY 便是 is DIFFERENT from all other such phrases.Guys thank you for your answers, but still your examples are not enoug. 
So what I can gather from your posts^
1)便是 is more formal and used mainly in literature, articles.  Not interesting because It does not uncover nature of 便.
2)正是 is 100% sure while 便是 is not 100%.  Not interesting because it does not uncover the nature of 便.
3)便 is more like "so" rather than "straingt" or "then" or "just". Now THIS IS interesting.!!!

If someone could read the article 
https://drive.google.com/open?id=0B7f68zPex4RieXlKMzZNdV9Ndm8
then maybe we all will have interesting answers for this question. Thanks

Answer

you may try understand right this way:
便是= so,it is...
正是= exactly is

Answer

Hi, Евгений!

I assume that both "正是” and "便是” here serve like the verb to be in English.

We use "正是" when we are certain.

“便是” is also used to show that you are certain (but "正是” sounds more certain).  We use it like "就是" (more formal than “就是”).

Also, you can use “正是” alone but "便是” usually cannot be used alone.

Example:
您是联合国派来的特使吗？
正是！

"便是” usually needs to be preceded and followed by some words.  Exception: 这便是！

I answer your question based on the assumption that both of them serve like the verb to be in English.

Thanks!

Answer

“便”是“即便，就，纵使、即使”的意思，“便是”就是“即使是，即便是，纵使是，就算是”等等的含义。

Answer

They both can mean " 就是”,which means " it is " in English .    
While  “便是”can also mean “即使，纵然”，which means " even though" in English .for example : 便是皇帝来了，我也不怕。besides, you can use " 便是” in a conditional situation to express a wish ，你若安好，便是晴天。which is equal to " if ..then .."。 
  "正是“ is  used when you are 100% sure about your saying ,which means " exactly " in English

Answer

In my view, they are exactly equal, but if you want to underscore something or somebody, 正是 is better.