CDW with excess
The excess is NOT necessarily a cash deposit or a lock on the credit card, but simply a clause in the contract that sets a limit of liability for damage to the vehicle. For example, a threshold of 500 € means that in case of damage, the lessee would be responsible only to a maximum of 500 €, all other damages are covered by the rental company.
CDW with no excess
Also known as comprehensive insurance "exclusions". It is very similar to the above but instead of setting up responsibility in €, sets out a number of elements not covered by insurance, such as wheels and crystals often, moons, mirrors, keys, etc.. Thus, in case of damage, the tenant should be held accountable for any damage caused to the items not covered by insurance exclusions. That is, it is a safe may like the franchise, but with the "uncertainty" of not knowing which is the maximum that you have to pay for damages.
Are you sure to franchise or not franchise?
As we see, is a much better insurance with excess as it indicates the maximum canitdad we would be responsible.
In any case, the two types of insurance also limit your liability. Per undoubtedly the best insurance models are cars with fully comprehensive insurance with excess € 0.