In some cases, if a family member is visiting and has permission from the insured to drive the family vehicle, there will be coverage if there is an accident, but the coverage may be limited. All policies should be reviewed to determine if there are any excluded drivers and any limitations on coverage for anyone driving the car that is not specifically named on the policy.
The main difference between collision and comprehensive coverage comes down to the question of what the driver controls. Collision insurance will cover events within a motorist's control or when another vehicle collides with your car. Comprehensive coverage generally falls under "acts of God or nature," or things that are typically out of your control when driving. These can include events such as a spooked deer, a heavy hailstorm, or a carjacking.