Covalent bonds form when two atoms share valence electrons,
while Van der Waals forces cause an attraction between nonpolar
molecules
Explanation:
A covalent bond is said to be formed when two atoms of the same or different elements share electrons. In an ordinary covalent bond, each bonding atom contributes one valence electron while in a dative covalent bond only one of the bonding atoms provides the shared pair of electrons.
Van Der Waals forces is the major intermolecular interaction between non polar compounds. Van Der Waals forces " are caused by correlations in the fluctuating polarizations of nearby particles"(Wikipedia).
