What's the difference between tough, difficult and hard?
For example, "it's tough/difficult/hard to tell..."
In this sentence, what's the difference between them?

Question

What's the difference between tough, difficult and hard?
For example, "it's tough/difficult/hard to tell..." 
In this sentence, what's the difference between them?

Answer

I think "tough" and "hard" are slightly less formal than "difficult". It is not rude or inappropriate to use "tough" or "hard", but in formal writing "difficult" is the best choice.

Answer

nothing.   virtually the same