What is the difference between thick film and thin film resistors?

Hint: Resistor is a device that acts as a two-terminal passive electrical component that is usually used to limit or control the flow of electric current in electrical circuits. Thin film resistors uses thin coating of material to produce resistance while thick film resistances uses thick coating on base of material to produce resistance.

Complete answer:
Thick film resistors and thin film resistors are usually distinguished by the resistive layer on the base. Even though thick film and thin film resistors look similar by appearance their properties and manufacturing process are very different. Thin film resistors have a thickness of $0.1$ micrometre or even smaller, whereas that of thick film is around thousands times thicker than thin film resistors.

The main difference between them is the method of applying resistive film onto the substrate. Thin film resistors consist of a metallic film that is vacuum deposited on an insulating substrate. Thick film resistors are made by firing a special paste, which is a mixture of glass and metal oxides, onto the substrate. Thin film resistors are generally more accurate, have a better temperature coefficient and are more stable. On the other hand, thick film resistors are preferred for applications where these high requirements are not needed.

Note: It is important to note that thin film resistors have a lesser tolerance than the thick film resistors. Thin film resistors have lower capacitance than thick film resistors. The temperature coefficient of thick film resistors is higher than that of thin film resistors.