In an Ionic compound, the electron sharing between two atoms is more like 20% : 80% to 0% : 100%
In these compounds the atoms gain positive and negative charges.
In a covalent bond, the electron sharing is like : 50% : 50% to 35% : 65%. So the electrons belongs to both atoms to a good extent. So both atoms are more or less neutral.
In ionic compounds, electropositivity and electronegativity of the two atoms differ a lot. In covalent compounds, they may not differ a lot.