WS-BPEL is very much a subset of what can be represented using WF. Think of WF as a "graph of activities" that can be transformed to virtually any workflow standard. I'll try to post a similar comparison between WS-BPEL 2.0 and XPDL 2.0 later this week.
BPEL Activity | WF Activity |
<receive> | Workflow start or WebServiceReceive |
<reply> | Workflow finish or WebServiceResponse |
<sequence> | Sequence |
<assign> | Code |
<while> | While |
<if>, <elseif> | IfElse |
<invoke> | InvokeWebService |
<scope> | Scope |
<flow> | Parallel |
<pick> | Listen |
<throw> | Throw |
<compensate> | Compensate |
<exit> | Terminate |
<wait> | Delay , Suspend |
<faultHandlers> | ExceptionHandler/ExceptionHandlers |