In a fully comprehensive insurance with excess, if you are responsible for the claim, you must take care of the amount established in this excess (the rest of the repair cost being covered by the insurer), the coverage of own damages and, also occasionally, theft, fire and windscreen damage.
In a fully comprehensive insurance policy without excess, the insurer is responsible for the total amount of the repair.
The fully comprehensive with excess modality allows you to take out a product with all risk coverage at a lower price.