Differences between Conductor and Insulator (Conductor vs Insulator)

A conductor is an object or a material that allows the flow of electric current in one or more direction. Metals like Iron, Copper and Aluminium are good conductors.

A insulator is a substance that does not allow the flow of electric current. Diamond, mica, glass and wood are insulators.

Conductor vs Insulator

Conductor	Insulator
Always allows the flow of electric current. Substances that requires only a small potential difference across them to cause a current flow	Insulator does not allow the flow of electric current. Current will not flow even when potential difference  is applied across them
Good conductors has large number of free electrons	Insulators do not contain free electrons or negligible free electrons
The conductivity is based on the free electrons due to metal bonding	No conductivity due to the absence of free electrons
The outer electron in the atom can be easily removed with a small potential difference applied	The outer electron in the atom cannot be removed with potential difference applied
Conductor is a material with low resistivity	Very high resistivity
Resistivity increases with increase in temperature	Resistivity decreases with increase in temperature
They have positive coefficient of resistance*	They have negative coefficient of resistance
In conductors, the conduction band is partially filled or it overlaps with the valence band	In insulators, the valence band is completely filled and conduction band is empty
The energy gap is zero or very small	The energy gap is very large
The electrical conductivity of a conductor decreases with increase in temperature because the rise in temperature increases the collision of electrons and disturbs its free flow.	Generally conductivity increases with rise in temperature as the electrons will go to the upper band. The availability of free electrons in the conduction band increases conductivity.
They will not behave as an insulator at any temperature	Rise in temperature lead to rise in number of free electrons thereby increases conductivity
Mixing of impurities causes increase in resistance and decrease in conductivity	No change in resistance and conductivity
Example of Conductor: Silver, Copper, Aluminium	Example of Insulator: wood, plastic, glass, diamond

*The resistance-change factor per degree Celsius of temperature change is called the temperature coefficient of resistance.