Interatomic does not necessarily mean intermolecular, unless it is a monoatomic molecule we are talking about (i.e., molecule and atom refer to the same thing. For example, Ar, He, Ne, Xe)
Generally, interatomic refers to atoms that are part of a molecule (example, force b/w Na and Cl in NaCl is interatomic)
Intermolecular refers to different molecules (For example, van der Waals force between two molecules of CH4 is intermolecular)