What does Wuhan Postal Bank’s recruitment of workers into Type C mean?

Postal Savings Bank employees are divided into Category A workers and Category B workers. and Category C workers. They are all contract workers. Category A belongs to the manager category. Category B belongs to the general category. Category B generally belongs to general employees who are called Category B after they become regular employees. Category C is what everyone calls labor workers, but in fact, the treatment of the three categories of workers is basically the same. There is no difference. Category C employees can be regularized. However, there are many requirements for becoming a full-time employee, such as academic qualifications, contribution to the industry, work ability, and rewards received. There are many standards and lines. I heard that Category C has worse pay than Category B. Generally, they are recruited from society with no connections and no background.