In most SAP landscapes the two work together. SAP Ariba handles sourcing and supplier collaboration, while SAP MM (or Sourcing and Procurement in SAP S/4HANA) handles purchase orders, stock and goods receipt.
SAP Ariba vs Coupa
Coupa is an independent cloud platform for business spend management, with procurement as one of its areas. Companies often consider it when they want a solution that does not depend on their ERP vendor. SAP Ariba is usually the stronger fit for companies that run SAP ERP or SAP S/4HANA and want standard integration and access to the SAP Business Network.
SAP Ariba vs Oracle Procurement
Oracle Procurement is part of Oracle’s cloud applications and suits companies whose ERP, finance and supply chain already run on Oracle. SAP Ariba suits companies with an SAP core system and a large supplier base that they want to connect through the SAP Business Network. The right choice depends on the ERP landscape, the process scope and the supplier base.