Why are there different types of temperature sensor?

Range and response differ. Digital sensors (DDI) cover -40 to 125 °C at ±0.3 °C and suit refrigerators, freezers and rooms. Thermistors cover -20 to 80 °C at ±0.3 °C. Thermocouples reach far colder and far hotter, from cryogenic storage up to oven temperatures, at accuracies that depend on the thermocouple type.

Choose wired sensors when you can run a cable and want the fastest update. Choose wireless when running cable is impractical; the transmitter sits outside the cold unit with the probe fed through the door gasket.

Immersible probes can sit in a bottle of glycol so the reading reflects stored product rather than the air, which stops door openings from looking like excursions.