I understand what a host is, but it is a little confusing what a service name’'s relationship to a host is and how they differ exactly. I searched and came up with nothing…
Sometimes the same words have different meanings depending on the context or who/how are they being used. I will try to give some definitions that will hopefully help you identify the concepts.
Host = Could be an IP address or a server name. Clients should perform a DNS look up to find out the real address of the server and use that information to establish a connection with the server.
Service name = Name that the XMPP server is using. This is typically the domain of the server. This value is used by the client when sending the . E.g. conference.myserver.com