Discussions have many threads. Chat programs and Moos have, perhaps, more of the disjointedness associated with conferencing, listservers and newsgroups. Conversations, however, do not develop over an extended period. Instead, they take place in real time. When connected to a chat room with, say 20 other people, I am reading and writing at the same time as those other people.
Moos function similarly to chat rooms in that participants are on-line at the same time.
Moos, however, provide a greater range of communication tools than chat rooms. Click on that hot link and you jump to another page. This page has other hot links. This is the basic metaphor for the World Wide Web. The internet is nothing more than a very large number of computers connected together.