The new world is SAP S/4HANA. SAP S/4HANA stands for SAP Suite for SAP HANA DB. You cannot install SAP S/4HANA - it is only the product name. You can install one of the SAP systems inside, for example SAP BW, SAP Front End Server - or SAP S/4HANA Server.
SAP S/4HANA Server is the name of the SAP system and SAP S/4HANA is the name of the suite. These terms often get mixed up in daily usage.
The SAP Business Suite consists of the solutions SAP ERP (Enterprise Resource Planning), SAP CRM (Customer Relationship Management), SAP SCM (Supply Change Management), SAP SRM (Supplier Relationship Management), and SAP PLM (Product Lifecycle Management).
SAP ERP includes SAP ECC (ERP Central Component), SAP XSS (Employee/Manager Self Services), SAP XECO (Accelerated ECommerce), SAP BW (Business Warehouse), SAP Enterprise Portal, SAP PI (Process Integration), and many more. These are installable and upgradeable units.
You cannot update or upgrade (to) SAP ERP in general, but you can upgrade (to) SAP ECC or SAP BW and so on.
SAP ECC was called SAP R/3 in older releases.
SAP ECC is not designed to take advantage of the SAP HANA DB. Yes, you can use an SAP HANA DB with an SAP ECC system. But to gain profit from the column store, the database procedures, the simplified data model, and so on, you have to use SAP S/4HANA Server, instead.
This figure, SAP_BASIS releases of SAP ECC and SAP S/4HANA Server, shows the releases of software component SAP_BASIS over time, reading from top to bottom.
This slide shows – as an example – the release of the software components of the newest SAP ECC system and SAP S/4HANA Server 2020.
SAP S/4HANA Server 2023 is part of SAP S/4HANA 2023.
SAP_ABA 75I and SAP_BASIS 758 are part of ABAP Foundation 2023.