Question

What are benefits of semiconductor over conductor

Answer 1

Conductors and insulators work in one way... either to insulate or to conduct. 
However, a semi-conductor can work both ways... meaning they can switch 'on' and 'off'. Transistor is a good example of a semi-conductor. 
Example of conductor: Electrical wires 
Example of insulatos: PVC used to insulate the circuit and prevent human contact with a 'live' conductor.

Answer 2

The Semiconductor device is made up of a material that is neither a good conductor nor a good insulator, it is called a semiconductor. Such devices have established wide applications because of their reliability, compactness, and low cost.