Polarity is determined by the difference in electronegativity between the atoms in a molecule. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.

* Oxygen (O) is more electronegative than sulfur (S).

* In H₂O, the oxygen atom attracts the shared electrons more strongly than the hydrogen atoms, creating a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. This creates a dipole moment, making water a polar molecule.

* In H₂S, the sulfur atom is less electronegative than oxygen, resulting in a smaller difference in electronegativity. This creates a smaller dipole moment, making hydrogen sulfide a less polar molecule.

Therefore, H₂O is more polar than H₂S.