A warranty is like a guarantee provided by the manufacturer (Dell, ASUS, etc.) that the device will work as it should for a specified period of time. It covers defects and includes repairs, and in some cases a replacement.
A standard warranty doesn’t cover any breakages that are caused by the owner (a student or parent for example).
Olive for Education 1:1 student device bundles include something very special, which is Accidental Damage Cover. This covers any breakages, even broken screens (with a limit of one breakage per year).
Insurance is a service that provides coverage against risks that of no fault of the manufacturer, such as theft, damage, loss, etc.