1, the mandatory of the two is different. Three liability insurance is not mandatory, but is essentially commercial insurance established according to the commercial insurance system. For car owners and insurers, more attention is paid to the dispersion of risks and the acquisition of insurance benefits. Whether to insure is the result of consensus between the two parties. Compulsory insurance is compulsory, similar to social insurance. Pay more attention to protecting the interests of third parties in time. All car owners are required to take out insurance, and insurance companies must take out insurance and may not refuse to take out insurance. 2. The principle of compensation is different. Three liability insurance is to determine the insurer's liability according to the fault liability. The specific compensation method is stipulated in the insurance contract, and the compensation shall be carried out in accordance with the contract regardless of personal injury and material loss. How much compensation does the insurer bear according to the accident liability of the insured in the accident? ; The liability of the compulsory insurance insurer is determined according to the principle of no fault, not according to the insurance contract, but according to the specific provisions of the law and the Regulations on Compulsory Insurance for Motor Vehicle Traffic Accident Liability. 3. The scope of compensation is different. The "three liability insurance" has done a lot of exemptions for the scope of compensation, including different liability exemptions and free odds, while the insurance liability of "compulsory insurance" covers almost all traffic accidents except intentional accidents, and there is no provision for free odds.

Article 21 of the Regulations on Compulsory Liability Insurance for Motor Vehicle Traffic Accidents

If a road traffic accident occurs in an insured motor vehicle, causing personal injury or property loss to the victim other than the person on board and the insured, the insurance company shall make compensation within the limit of compulsory motor vehicle traffic accident liability insurance according to law.

The loss caused by the road traffic accident is intentionally caused by the victim, and the insurance company will not compensate.