The main differences between the warranty period and the defect liability period are as follows: 1. The starting time of the calculation date is different. 1. The starting date of the warranty period starts from the date when the owner's engineer issues the project completion certificate; 2. The defect liability period shall be calculated from the date when the project passes the completion (handover) acceptance; If the project cannot be completed (handed over) for acceptance within the specified period due to the Employer, the project will automatically enter the defect liability period 90 days after the Contractor submits the completion (handover) acceptance report. 2、 The warranty period is different. 1. Article 40 of the Regulations on the Quality Management of Construction Projects issued by the State Council stipulates that "under normal use conditions, the minimum warranty period of construction projects is: (1) infrastructure projects, foundation projects and main structure projects of housing construction, which is the reasonable service life of the project specified in the design documents; (2) 5 years for roof waterproof works, toilets, rooms and exterior walls with waterproof requirements; (3) Heating and cooling system, 2 heating and cooling periods; (4) 2 years for electrical pipeline, water supply and drainage pipeline, equipment installation and decoration works. 2. The defect liability period is generally 6 months, 12 months or 24 months, which shall be agreed by the Employer and the Contractor in the contract management. 3、 The two follow different legal bases. 1. The warranty period follows the Regulations on the Quality Management of Construction Projects; 2. The defect liability period follows the Model Text of Construction Contract of Construction Engineering. Then let's extend this problem to: during the defect liability period, the contractor shall be responsible for the repair of defects caused by the contractor, and bear the identification and maintenance costs. If the Contractor does not repair or bear the cost, the Employer may deduct the retention money as agreed in the contract, and the Contractor shall be liable for breach of contract. The Contractor shall not be exempted from the compensation liability for general losses of the project after maintenance and bearing the corresponding costs. The starting date of the defect liability period must be the actual completion date of the project, and the corresponding calculation time of the project care obligation period is from the project acceptance certificate issued by the owner. For projects with more than one handover date, the defect liability period shall be calculated from different handover dates. The project quality warranty period and defect liability period are both set to ensure the project quality. The difference between the defect liability period and the warranty period is mainly reflected in the length of their periods and the determination methods. The defect liability period is relatively short, and the specific period can be agreed by both parties through consultation. The quality assurance period is mandated by the state, which is longer. For example, waterproof works can be guaranteed for five years.