Imagine checking a customer inquiry from SAP CRM using the SAP Portal interface, and then moving to SAP GUI to check the stock availability in ERP. Completely different interfaces are used with their own style and features. They have different buttons, menus, and tools. With SAP Fiori, users work with just one design.SAP GUI is still available with the on-premise edition, and can be used alongside SAP Fiori, but we recommend using SAP Fiori in order to take full advantage of the features of SAP S/4HANA.Not all transactions from ERP are converted to SAP Fiori applications, so the SAP GUI must still be used in some cases. However, SAP S/4HANA Cloud uses only SAP Fiori applications,and there are no classic SAP GUI screens.