yes, I see that now. Does the d^2 mean something? or just signifiy second derivative, i can see how the dx squared would be like acceleration is seconds^-2
They are certainly not the same; don't think of them as exponents or fractions at all it is very misleading. It is just notation to relay the fact that you have acted the operator [itex]\frac{\mathrm{d} }{\mathrm{d} x}[/itex] on [itex]f[/itex] at [itex]x\in \mathbb{R}[/itex] twice.