Oracle Big Data Discovery Cloud service (BDDCS) is a single-tenant Platform as a Service (PaaS) offering in Oracle Public Cloud (OPC).
Here is how BDDCS relates to BDCS:
Oracle Big Data Cloud Service (BDCS) is a "container" for the BDDCS instance. BDCS is a platform for running workloads on Hadoop systems, and for the development of Big Data applications. A BDCS starter pack consists of six hosted nodes. You can add more nodes if needed. Each BDCS instance includes access to the Cloudera Hadoop Distribution (CDH) Enterprise Data Hub Edition, and Oracle Big Data Connectors.
Oracle Big Data Discovery Cloud Service (BDDCS) is deployed into an existing BDCS cluster instance in the same Identity Domain. It occupies one node in the BDCS cluster instance. BDDCS provides catalog, exploration, and visualization of data stored in a BDCS cluster.