The difference between a conductor and an insulator lies in their ability to allow the flow of electric current. Conductors, such as metals, permit electrons to move freely, enabling efficient transmission of electricity. Insulators, like rubber or glass, restrict electron movement, preventing current flow. This property is essential in electrical applications, where conductors are used for wiring and electrical components while insulators provide safety and protection. Understanding these differences is key to designing effective electrical systems and to various technological advancements.