The difference between CDW and LDW is that a CDW, or collision damage waiver, keeps a car-renter from being held responsible for damage to a rental car caused by an accident but not by theft. On the other hand, LDWs, or loss damage waivers, cover rental car damage caused by both accidents and theft. Some rental car companies, like Avis, use the terms CDW and LDW interchangeably, so it's best to read the coverage details carefully.
Collision damage waivers and loss damage waivers are optional types of coverage sold by rental car companies and third parties. Drivers can usually buy these waivers at the rental car counter for around $10-$30 per day. However, it's important to note that collision and loss damage waivers do not provide liability insurance, which pays for damage you cause to others and their property. Instead, rental cars in most states automatically come with liability coverage. Drivers with standard car insurance policies will usually have liability insurance from their personal insurer, too.
To decide if you should purchase a CDW or LDW, check out WalletHub's complete guides to collision damage waivers and rental car insurance.