Is there a difference between $\displaystyle (\delta x)^2$ and $\displaystyle \delta x^2$ ?
Someone told me they are the same but i doubt it.
If $\displaystyle \delta$ is simply another variable, then your question has already been answered. However if you were asking if $\displaystyle (dx)^2=dx^2$ where dx is a differential, then this is sometimes the case. You'll find that in many books (especially physics books) a squared differential is sometimes denoted as dx^2 rather than (dx)^2, or at least that is the case in my experience. If this is the case, then they are the same.