Answer:
Ionic bonds are usually between a metal and a nonmetal and involve the transfer of electrons. Covalent bonds are typically between two nonmetals and involve the sharing of electrons.
Step-by-step explanation:
When elements bond together ionically, they transfer their valence electrons to another element to satisfy the octet rule and create full shells of 8 electrons. Metals usually have low electronegativity and ionization energy and can more easily give up an electron to a nonmetal with higher electronegativity and ionization energy.
When two nonmetals bond, their electronegativities are close enough in magnitude that neither element can "claim" the valence electrons, so the electrons orbit back and forth between the elements in the bond.