INERTIA OF MOTION:
if any body is at motion it tends to be in motion unless and until an exterior force is applied on it.Ex:if a ball moves after some time it stops because of air and friction.
INERTIA OF REST:
if any body is at rest it tends to be at rest unless and until an exterior force is applied on it to move.Ex: a paper is kept on a table, if fan is switched on then the paper moves because of air(exterior force)
HOPE IT HELPS....