See the ion is a proper charged particle, but dipole is a neutral olecule which is having polarity in it . the dipole is having temporary charge where as the ion is having a permanent charge.
Now lets see the cases
Case 1 :- Ion – dipole attraction
Here a permanent ion is attracting a dipole and there are strong electrostatic forces of attraction.
Case 2 :- Dipole-dipole attraction
In this case the attraction is not as strong as in above case, because the force in dipole-dipole attraction is less strong.