How can we decide nature of bond from difference of electronegativity?

Electronegativity and nature of chemical bond

The most important point to be noted for electronegativity is that it  gives information about the nature of bond not about the atom. We can say it is a bond property not a property of a atom. Electronegativity values help in deciding the nature of bond. We can decide the nature of bond with following rules.

Electronegativity difference                                    Nature of bond

Less than 0.5 or 0.5                                                  non polar

Between 0.5 and 1.7                                                  polar

Greater than 1.7                                                         ionic