What is the difference between a credit card hold or a deposit?
No difference. The card hold or deposit are a hold applied by companies to cover their backs in case they have to charge you for fines or penalties. And each company decides whether to retain it or not.
The deposit, is an amount of money, which varies depending on the type of insurance and the category of the car. It is left as a guarantee and is returned once you deliver the vehicle in the same conditions in which you picked it up.
The deposit money, or lock, is usually withheld on your credit card. While it is blocked, the rental company will not move it from your account, but you will not be able to use it either.
The deposit is NOT necessarily a cash deposit, nor a credit card lock, but simply a clause in the contract that establishes a monetary limit of liability in case of damage to the vehicle. You can hire insurance to eliminate the deposit.
When do I get back the money from the deposit when I rent a car?
If there were no problem and you return the car in the same conditions in which you picked it up, they will unlock the amount retained and they will not charge you anything. Depending on the company, this can take from a few days to a month, or months, as they usually wait a while in case of a fine.
Keep in mind that, while the money is blocked, the rental company will not take it out of your account but you can not use it either.
On the other hand, the time it takes to be available again in your account also depends on the communication between banks.
If you have returned the car in good condition, but you see that you have not unlocked the money yet: do not worry, it usually takes between a few days and a month.