Limit switches and thermostats are both electrical controls used in HVAC systems, but they serve distinct purposes. Limit switches are designed to protect the system from overheating or overcooling by automatically shutting off the system when a specific temperature threshold is reached. They are typically used as a safety device to prevent damage to the system or its components. Thermostats, on the other hand, are responsible for controlling the temperature of the space by signaling the HVAC system to turn on or off as needed. While both devices are temperature-sensing, their functions and applications differ, with limit switches focused on safety and thermostats focused on temperature control.