Ejb-ql is compliant with J2EE specs, specifically whatever is in EJB specs is there is available in ejb-ql.
But with Jboss-Ql you can also do the same thing but Jboss-ql is more advanced and has gone beyond the steps, Example in j2ee-1.3 in yr qeury you can't use 'Order by' clause with jboss-ql you can do that with more advanced features in it.
Ejb-ql query descriptors are in ejb-jar.xml
Jboss-ql query descriptors goes in jboss.xml.
But since these advanced features are supported by Jboss server only, hence results in porting issues of application on other application servers.
I hope this clarifies some of yr doubts.