$y'' + y =\mu_\pi \big(t\big)$
$y''+y= \delta (x- \pi )$
wih initial conditions:
$y \big(0\big) =0$
$y' \big(0\big) =0$
It is obvious to me that the first equation is a Heaviside distribution and the second is a dirac delta funtion. I am not sure if that is the difference between them or I need to perform Laplace transforms to see the difference. Also I am not sure of any physical situation which would describe these eqautions. Any help would be greatly appreciated.