Alibaba and Taobao belong to the Alibaba Group. Alibaba is a business-to-business website. Taobao is a customer-to-customer website (users on Taobao can act as both buyers and sellers). Alibaba does wholesale for large customers, which is a transaction between large merchants and small merchants, in bulk. Taobao is a transaction between merchants and customers. The former serves small merchants, while the latter serves direct customers.