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