THERMISTER
Thermistors are thermally sensitive resistors (thermal resistor) the function, is to exhibit a large, and precise change in electrical resistance when subjected to a corresponding change in temperature. Negative Temperature Coefficient (NTC) thermistors exhibit a decrease in electrical resistance when subjected to an increase in body temperature and Positive Temperature Coefficient (PTC) thermistors exhibit an increase in electrical resistance when subjected to an increase in body temperature. Because of their very predictable characteristics and their excellent long term stability, thermistors are generally accepted to be the best sensor for many applications.

THERMISTER WIRING
The resistance of thermistors is is normally several times greater than any sensor wire resistance.
The sensor wire resistance has a negligible effect on the temperature reading and thermistors are almost
always connected in a 2-wire configuration.

NEGATIVE TEMPERATURE COEFFICIENT (NTC)
NTC thermistor is one in which the resistance decreases with an increase in temperature.

POSITIVE TEMPERATURE COEFFICIENT (PTC)
PTC thermistor is one in which the resistance increases with an increase in temperature.

RTD
Resistance Temperature Detector RTD's are positive temperature coefficient (PTC) sensors whose resistance increases as temperature increases. The main metals in use are platinum and nickel. The most widely used sensor is the 100 ohm or 1000 ohm RTD or platinum resistance thermometer. RTD’s are the most accurate sensors for industrial applications and also offer the best long-term stability. A representative value for the accuracy of a platinum resistance is +0.5 percent of the measured temperature. After one year there may be a shift of +0.05°C through aging. Platinum resistance thermometers can cover temperature ranges from -200 to 800°C.

BALCO
Balco Series temperature sensors incorporate a wire wound RTD sensor, which provides a predictable output over the specified temperature range of -40 to +240°F.
Balco resistance 1000ohm ±1% at 70°F (20°C).

THERMOCOUPLE WIRING
Unlike RTD’s and thermistors thermocouples have plus and minus legs so polarity must be observed. They can be directly connected to a local 2-wire transmitter and copper leads can be run back to the receiving instrument. If the receiving instrument is capable of accepting thermocouple inputs directly you must use the same thermocouple wire or thermocouple extension wire all the way back to the receiving instrument.

This is not intended to be "complete" information, do your research for your specific application.