I get asked often which business process standard an organization should use; BPMN or BPEL? As I explain to folks, they both have strengths. Here is a great article that helps understand the benefits of both and where to use them. The good news is that, with Oracle SOA Suite and BPM suite, you have the option and flexibility to use both in the same SCA model and runtime container. Good stuff.
Here is the great article that Mark Nelson wrote:
The right tool for the right job
BPEL and BPMN are both ‘languages’ or ‘notations’ for describing and executing business processes. Both are open standards. Most business process engines will support one or the other of these languages. Oracle however has chosen to support both and treat them as equals. This means that you have the freedom to choose which language to use on a process by process basis. And you can freely mix and match, even within a single composite. (A composite is the deployment unit in an SCA environment.)
So why support both? Well it turns out that BPEL is really well suited to modeling some kinds of processes and BPMN is really well suited to modeling other kinds of processes. Of course there is a pretty significant overlap where either will do a great job