[jdev] Difference between "Feature Negotiation", "Service Discovery" and "Entity Capabilities"?

[Guus der Kinderen]

I'm struggling to see what JEP-0115 "Entity Capabilities" adds to the
Jabber protocol that hasn't been provided by either JEP-0030 "Service
Discovery" or JEP-0020 "Feautreu Negotiation." Can someone point me out
the differences, maybe combined with a practical example?

 - Guus