There are essentially two types of network:
(a) Peer-to-Peer and (b) Client/Server
Home networks are "peer-to-peer" with all connected computers having an equal status in the network. The fact that you elect to store all of your files in a particular computer and then "share" the relevant Folders/Drives doesn't alter the fact that it is still a "peer-to-peer" network.
In a "Client/Server" network, the client PCs will be running an operating system such as XP Pro and the Server will be running a dedicated server Operating System, such as Microsoft Small Business Server.