Is there a difference between a tempco resistor and a thermistor?
Thermistors have a much higher variation of resistance, a thermistor can change from the 100Ω's to kΩ's (and 100kΩ's) over a range of 100C&deg;. 

A tempco resistor usually has its resistance change by 100ppm's or 1000ppm's which would be less than an ohm over a 100C&deg; range