The second component is residual liability insurance, which protects you in case you are sued by someone involved in the accident. No-fault liability coverage is usually referred to in a series of three numbers. That means that your first claim will go to your medical carrier and the auto insurance will cover the excess. While state law says this coverage is optional, lenders often require it to protect the vehicle, at least until it is paid off. It's the most expensive kind of collision coverage.
Standard collision pays for damages regardless of who is at fault.
The deductible always applies. Limited collision pays only if you are not substantially at fault and it could have a deductible. It, too, has a deductible that can be increased to reduce the premium. They also advise against dropping comprehensive coverage unless your car is worth less than the book value or if you're fortunate enough to be able to replace the car out of pocket. It is optional, but highly recommended by consumer advocates.