spherical[x_] = -(Sqrt[4 - (x^2)])parabolic[x_]  =   -2 + ((x^2)/4)\(r\  = \ 0.1
\)\(	Plot[{spherical[x], parabolic[x]}, \ {x, \ \(-r\), r}]			
      Plot[{spherical[x] - parabolic[x]}, \ {x, \ \(-r\), r}]\)

\(\(			Plot[spherical[x] - parabolic[x], \ {x, \ \(-1.1\), 1.1}]\)\)