What is the difference between PT100 , PTC & NTC?

PT100 is an RTD (Resistance Temperature Probe) made of Platinum metal which has a resitance value of 100 ohms at zero degrees celsius.  While NTC (Negative Temperature Coefficient) and PTC (Positive Temperature Coefficient) are both types of Thermistor. NTC have resistance that decreases with increasing temperature. PTC exhibit increased in resitance with increasing temperature. Thermistor have a very high sensitivity, and therefore are very responsive to changes in temperature with faster response time than RTDs, but smaller temperature range than RTDs. In short both RTDs and Thermistor are electrical thermally sensitive resistors, they are which changes with temperature. Both are useful for specific design application.