No. A class II hitch is rated to 3,500 lbs. A class III may be rated the same, but is often rated at 5,000 lbs or higher. A class III hitch has a 2" receiver opening which allows you to carry a...
Make sure to check the ball size and hitch size are the same first. Other then that yes, it just means the ball can withstand less weight then the receiver hitch.