SAP Business Suite on HANA (SoH) came before S/4 HANA. As the name suggested, the traditional SAP ECC solution is available on SAP HANA. It has all the traditional functionality of an ECC environment but the database is a HANA engine.
Because SAP ECC predates SAP HANA, distributors currently using it generally started on other databases (DB2, Oracle, etc.). When SAP ECC customers perform a SAP HANA migration without changing the back end, it becomes SAP Business Suite on HANA. This lets distributors benefit from the performance boost of SAP HANA without restructuring the application layer.
Distributors like Graybar, PrimeSource, Cheney Brother, and others, have moved to SoH as an interim step to an eventually move to S/4 HANA. This near-term simplification strategy allows them to get their feet wet with SAP HANA, get the performance boost, and prepare for a long-term optimization strategy to S/4 HANA.
Distributors can also prepare for a smooth journey to S/4 HANA my selecting extended SAP solutions as the business requires additional edge functionality to meet business imperatives. Choosing SAP solutions like IBP for advanced supply chain planning, Hybris Commerce for B2B, eWM for advanced warehouse management, or Hybris Sales for SFA, eliminated the need for interfaces to SAP ECC, and enables a graceful migration path to an S/4 HANA landscape that includes those solutions.
Alternatively, distributors running SAP ECC that select non-SAP solutions for extended capabilities put themselves in risky and costly position. Selecting SAP competitive solutions like JDA, WebSphere, Manhattan, or Salesforce, creates an environment for complexity.
This awkward S/4 HANA transition strategy has users in multiple systems, creates a landscape of constant upgrades from multiple vendors, and poses data replication integrity issues. Information in this landscape also delivers latent information due to the need for batch jobs to move data.
In summary, net new customers should move directly to SAP S/4 HANA, existing customer can prime themselves for SAP S/4 HANA by taking a preparatory step to SAP Business Suite on HANA.