is it that weblogic is too lenient while checking the method signatures but jBoss is not ?
Going by the error message it does appear that WebLogic allowed you too deploy the application even though the method did not strictly follow the spec. The verification message does tell you what has to be done to fix this:
Bean : XYZBean
Method : public XYZPK ejbCreate(some VO)
Warning: The throws clause must define the javax.ejb.CreateException.
By the way, you can disable bean verification (but not recommended) by setting the following property to false (by default this is set to true):
in %JBOSS_HOME%/server/< serverName>/deploy/ejb-deployer.xml