What's the difference between the first, second and third social security files?

First-class insured: any designated medical institution in this city for medical treatment. Second-class insured persons: outpatients seek medical treatment in the binding community health center, inpatient departments seek medical treatment in any designated medical institutions in the city, and outpatients seek medical treatment in designated medical institutions for serious illness. Third-level insured persons: outpatients seek medical treatment in the binding social health center, and inpatients and outpatients seek medical treatment in prescribed medical institutions for serious illness.