Learn English – Difference between “on time” and “just in time”

Both phrases are valid, but they both mean slightly different things. The phrase "impossible is nothing" evolved from "nothing is impossible".

Consider the following dialogue:

Person A: We can't do X - it would be impossible!

Person B: Nothing is impossible.

In this scenario, person A claims that doing X is not possible, but person B claims that this is not true. "Nothing is impossible" is a rejection of the claim that X cannot be done, by suggesting that problems abandoned for being "impossible" are typically "hard" rather than "impossible".

The phrase "impossible is nothing" is a very modern extension of this phrase into a boast, as shown below:

Person B: Nothing is impossible.

Person C: For me, impossible is nothing.

In this scenario, person B claims as before that many things people think are impossible are merely hard. But person C is saying that such problems are nothing - that is, trivial - for him.

So in summary, "Nothing is impossible" is a motivational phrase rejecting claims that something is "impossible" by claiming that it is only "difficult" rather than "impossible".

But "Impossible is nothing" is a boast - a claim that the speaker is able to easily perform feats that other people would think impossible to achieve.

In your first example, you would just use above, as an adverb is all that is needed. But it really only describes what is directly above.

In your second example, from above is not helpful because it is not specific as to what you are referring to. You should point to the specific location.

When using from above, from is a preposition, so I expect an object in that phrase. For example:

From above the trees, I could see the distant horizon.

The locations are specific. Also motion is often involved:

The birds flew from above the trees to the roof of our house.

There are some idiomatic usages though, for example:

Their new baby was a gift from above. (meaning from heaven)