Let's use the aftermath of Superstorm Sandy as an example to illustrate the differences between collision and comprehensive. Within that storm, let's consider two events that might have happened: 1) a heavy tree branch fell on your car, or 2) you swerved to avoid a falling tree branch and wound up crashing into a tree. In the first event, you had no control over when or why a tree branch would fall on your car. This kind of accident would get reimbursed under your comprehensive policy. In the second situation, you were driving the car and ultimately swerved into the tree, which makes it a collision, and collision insurance therefore pays for the damages. Events like the hypothetical ones stated above are why it's important to differentiate between the two types of coverage.
Auto insurance premiums depend on the insured party's driving record. A record free of accidents or serious traffic violations typically results in a lower premium. Drivers with histories of accidents or serious traffic violations may pay higher premiums. Likewise, because mature drivers tend to have fewer accidents than less-experienced drivers, insurers typically charge more for drivers below age 25.