What do the similarities and differences of the three substantive laws mean respectively?

The common ground is that the general principles and objectives of organization and management are the same. These three standards use the same process model structure, which is similar for convenience. The principle of the system is PDCA (Plan, Implement, Check and Improve) cycle. The difference is that ISO900 1, ISO 1400 1 and ISO4500 1 are all important parts of the overall management of the organization, which regulate the activities and behaviors of the organization from different aspects and aim at different people.