Doudian and expert sales are two models of Douyin e-commerce. Doudian is Douyin's e-commerce platform, where merchants can open their own stores and sell goods. Expert sales is to promote products through Internet celebrities and experts on Douyin, using their fan base and influence to help merchants sell goods.

The difference between the two is that Doudian is a store operated by the merchant himself, while expert sales relies on the influence of Internet celebrities and experts to promote products.