Difference between uninsured motorist and underinsured motorist coverage?

This is actually ONE coverage, serving two different purposes. You will often see this expressed on a declarations page as UM/UIM. Uninsured motorist coverage is self explanatory. YOUR uninsured motorist coverage on YOUR policy will pay for damages to your insured automobile when an 'at fault' vehicle does not have any insurance coverage to pay for your damages. UIM is UnderInsured Motorist coverage and would be available when the damages to -your vehicle exceed the amount of coverage in effect on the at fault party's liability coverage. This is an important coverage to have; very few state minimum liability limits are adequate anymore to offer full protection to owners. Rising auto costs and auto parts costs, plus the lower threshold to declare a total loss make higher UIM limits a sound decision.