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.
Drive Other Car insurance is similar to an Individual Named Insured Endorsement. If you need to borrow, test drive, rent, or lease a vehicle, Drive Other Car insurance will extend the coverages you’ve purchased for your commercial auto insurance policy - like Liability insurance, Physical Damage insurance, Medical Payments, and Uninsured Motorist Insurance, to a non-owned car.