Please see Jan's comment. The thread you already found is already good. You need to compare the two modelling standards, not an engine product and a standard.
BPEL was popular in SOA times, for service orchestration in full automated processes. BPEL can be excuted by a BPEL engine. There are different products offering this capability.
Early plans to be able to map BPMN 1.0 (Notation only, no model) mostly failed. This was one motivation for BPMN 2.0, which also standardases the model, not only the notation. Due to its block orientation and lack of support for human tasks BPEL did not cover all BPM/Workflow requirements. I would say BPEL is dying if not already dead. I would not spend time on it today. Of course that is a personal, biased opinion.
BPMN 2.0 on the other hand is a mature OMG standard, stable since 2014, works for a variety of process management and automation needs and has a wide and growing adoption.
Camunda offers process engine products, which interpret and execute process models based on the BPMN 2.0 standard. There are other product, which also use this modelling standard. engine specific attributes for process automation beyond the standard may differ between vendors. It depends on how closely the vendors are implementing the standard. See for instance https://www.omgwiki.org/bpmn-miwg/doku.php