There are 3 products.
A charge controller or charge regulator is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panels going to the battery.
PWM charge controllers for use with 12V and 24V panels in isolated systems. MPPT charge controllers allow you to take full advantage of the photovoltaic panel power, usually 20 to 30% more than with a PWM controller. They also allow the use of microgeneration panels in 12V, 24V or 48V systems. Whenever possible, choose a charge regulator with display. The information they present lets you know if your system is producing well and working properly.