The term e-procurement is often associated with other terms like supplier exchange and supply-chain management. E-procurement systems may involve a component of competition and price analysis. One way to understand conventional e-procurement is that it is different from consumer e-commerce, where the dominant model involves shopping carts and user-friendly Web-delivered interfaces. With e-procurement, the interface is more often set up in a way that facilitates commercial transactions, with specialized invoicing, purchase orders, shipping and payment tools. E-procurement systems also differ depending on whether or not they're used in the public sector or in government.