People use commercial umbrella liability and excess liability insurance interchangeably, but they are different. Both these policies have a similar purpose — extending the limits of standard liability coverage. But the kind of coverage they provide is what differentiates them.One of the main differences between umbrella liability and excess liability is that umbrella coverage can be applied to multiple policies whereas excess liability cannot. Additionally, umbrella liability provides coverage for claims that are not included in the primary policy. But excess liability is restricted to coverages included in the main policy.