What is the difference between Shanghainese and locals?

Shanghai people come from all over the world. If you look up three generations of Shanghainese, there is not a single Shanghainese. Those who claim to be Shanghainese cannot obtain genealogy certification. They are basically immigrants from Haimen Qidong, Jiangsu Province before liberation. They have registered for a long time. The place of birth in the book is written as Shanghai. The locals are farmers in the suburbs of Shanghai, and the locals are Shanghai natives.