by VanessaE » Mon Jun 10, 2013 04:58
Clients will never show any mods installed as the mods' code is run on the server only. All the clients receive are textures, sounds, node definitions, in-game events, etc. When you run the /mods command, you're actually asking the server what it has installed.
Clients of course can have their own mods, but those mods will only run in local-only single-player mode. Local mods will not be used at all when you are signed into a server.