Channels contain a variety of properties, some read-only, others read-write. Some duplication of functionality is present, in that PROP commands can be used to change certain attributes that were previously only changeable by commands.
Nicknames contain a variety of properties, some read-only, others read-write. Some duplication of functionality is present, in that PROP commands can be used to change certain attributes that were previously only changeable by commands.
You can also use '/uprop <value>' in the place of '/prop <nickname|GUID> <value>'.