Why does ozone have an electrostatic potential map similar to that of SO2?
Resonance structures of $\ce{SO2}$ and $\ce{O3}$.



As you can see from the diagram $\ce{O3}$ and $\ce{SO2}$ are isoelectric and have the same shape and this accounts for their very similar electrostatic potential maps. Both molecules are polar although $\ce{SO2}$, with a dipole moment of 1.62D, is more polar than $\ce{O3}$ (0.53D). As the diagram shows, the polarity of both molecules is due to the their trigonal planar shape with a formal positive charge on the central atom.