What is the relationship between China Southern Airlines and Sichuan Airlines?

It doesn't matter. Official website shows that China Southern Airlines Co., Ltd., headquartered in Guangzhou, was founded in 1995, with blue vertical tail inlaid with red kapok as the company logo. It is the airline with the largest number of transport planes, the most developed route network and the largest annual passenger traffic in China. Established in 2002, Sichuan Airlines Co., Ltd. is located in Chengdu, Sichuan Province, and is an enterprise mainly engaged in air transportation. Sichuan Airlines and China Southern Airlines are independent airlines in China's civil aviation industry, so they have nothing to do with each other.