The SAP Graphical User Interface (GUI) is the front-end program used to access SAP systems. Several variants of the SAP GUI are available and are adapted for use in different environments. The SAP GUI program connects the front-end computer to a specific SAP system. To start the SAP GUI, SAP provides another program, SAP Logon. When the user launches SAP Logon, a screen displays a list of available SAP systems. This list is derived from a file on the front-end computer, and is preconfigured and made available to users.
SAP Easy Access
When you work with your SAP S/4 HANA system, you are able to start the SAP Easy Access menu. Here, you can select transactions via a menu path or through executing the transaction code. If you migrated your "old" SAP ECC system to SAP S/4 HANA, you could opt to work with the classic SAP GUI transactions.
The Project Builder appears the same way as in SAP ECC. The design has been adopted to the new themes, but the functionality remains the same.
The Choice is Yours
It is up to you which system access you prefer. Most SAP S/4HANA scenarios can be reached via the SAP Fiori launchpad. As an alternative, you can use SAP Business Client with standard Web Dynpro or the SAP GUI for HTML transactions. If users do not want to work with SAP Fiori or SAP Business Client, they are still able to open the classic SAP transactions.