SOA is a logical orchestration process language that allows you to orchestrate your processes without being linked to any platform or language. It belongs to the Service Orchestration family.
An SOA BPM is a model that allows you to assemble software components that are designed by a WSDL. Therefore, you can import WSDL files in an SOA BPM.
When you decide to use the Service Oriented Architecture process language, you generally do not know yet which platform you are going to use to execute your processes. However, SOA allows you to design the Web services orchestration by providing access to service providers, service interfaces and operations.
You can afterwards use the Change Target command (see Changing the Process Language) or Model-to-Model Generation (Generating Other Models from a BPM) to change to the appropriate platform or language.