Difference between 「～てからでないと」and 「～ないことには」


Both of these grammar can be translated to English as

[code]

    A～てからでないと/～ないことにはB = Unless A is done, cannot do B
    
[/code]

From what I can find,

～てからでないと stresses the order or sequence of actions, that until A is done, B
will not happen

～ないことには stress the requirements of the action, that A must be a condition that
is satisfied, in order to do B

However I'm still not confident if these nuances are accurate, and I cannot
distinguish its usage in certain sentences.

> 1) きちんと勉強し **てからでないと** 、いい仕事を見つけられない。(until you study?)
>
> 2) きちんと勉強し **ないことには** 、いい仕事を見つけられない。(if you don't do the action of
> studying?)
>
> Unless you study, you can't find a good job.
>
> 3) 塩は砂糖をいれ **てからでないと** 、甘みが野菜に染み込まないよ。(until you add sugar to the salt)
>
> 4) 塩は砂糖をいれ **ないことには** 甘みが野菜に染み込まないよ。(if you don't add sugar to the salt)
>
> Unless you add sugar to the salt, the vegetables will not absorb its
> sweetness.

Can someone please tell me if I'm understanding this correctly, and are they
interchangeable in all cases?




～てからでないと/～ないことには = Unless A is done, cannot do B

  1. ～てからでないと - After 〜 is complete.
  2. 〜ないことには - Before someone starts doing 〜.

When no one knows what's going on at the end and things are happening or sure
it will happen, in these case we use #1. In other word, "Let the things done
first!"  
「終わったらわかる」

When the one doesn't start doing or even not trying, the thing won't start
anyway, in these case we use #2. In other words, "Let the things begin
anyway!"  
「始めたらわかる」

