Radiators and intercoolers are both devices used to cool fluids, but they work in different ways. A radiator uses heat transfer to dissipate heat from the fluid inside it, while an intercooler uses forced convection to cooled the fluid passing through it. In a car engine, for example, the radiator would be used to cool the engine's coolant, while the intercooler would be used to cool the air that has been compressed by the turbocharger.