What's the difference between Zhongshan Social Security and Foshan Social Security?

Part of social insurance in Zhongshan and Foshan is based on the local average monthly salary (8% for old-age insurance and 2% for medical insurance). The average monthly salary in Foshan is higher than that in Zhongshan, so there is a difference in payment. In addition, some people feel that the economic situation is better, and they can pay more or less (pay more insurance premiums and pay less in the future), and at most they can pay three times less (at least 60%).