What is the electronegativity for a covalent bond?
The difference in electronegativity between the two atoms must be less than 1.7. It is the "small" differences in electronegativity that forms. a covalent bond.
In a covalent bond the electron density is shared between the two atoms. This means that the pull on the electron density being shared is " somewhat " equal.
In a ionic bond the electron density is mainly transferred to the one atom with the greatest electronegativity. The difference in electronegativity is so great that the sharing of the electron density is very unequal.