Client/Server networks are composed of many client computer and at least one server. Information saved to the server by a user using a client computer can be accessed by the same user on any other client computer on the network. System Administrators can control the entire network via a centralized location, (the server), making the job of changing settings on files or individual users very easy. This solution is however, very expensive, as the computers used as servers and the I.T. Professionals hired to setup and maintain them, are generally costly.
P2P (peer-to-peer) networks are easier to setup and cheaper to maintain, but generally harder to administrate. They use a hub to connect the peer computers to each other. All you need to create a P2P network are the peer computers and their IP addresses, a hub, and some network cable. Files are shared directly between computers, while each system is separate. Changing permissions is much harder on a P2P though, as an Admin must go to each computer physically to change settings.