Wheel alignment and balancing are two inter-related but completely different services and concepts. One can’t be done correctly unless the other is already correct. Tire or wheel balancing is the act of counter-weighing a tire to compensate for minor imbalances between the tire and wheel assembly. It’s normally done on a machine with the tires off the car. Wheel alignment is the process of ensuring that the geometric angles of caster, camber and toe are correct. Caster pertains to the angle of the two connection points for the kingpin assembly. Camber describes the angle of your tires as referenced to vertical. Toe is the angle of your tires in reference to the centerline of the vehicle.
For more info, see A Tire Alignment Guide: Cost, Benefits and Frequency