A file server may be either dedicated or non-dedicated.
A dedicated file server means that there may be a specific computer server that fulfills this function, typically for a larger network, and has specialized hardware and software to handle the greater workload. This may include more hard drive memory storage, better cooling systems, better security such as limited physical access, and specialized software contained within special server operating systems.
A non-dedicated file server just means that the computer functioning as a file server isn't used exclusively as such, and may also be used for other purposes, such as a workstation. This is more typical of small-scale systems, such as at home or in a small business.
Beyond that distinction, the varieties of file servers are characterized by the method of filesharing used within the network. These include use of FTP (File Transfer Protocol), SMB/CIFS protocol, HTTP, or NFS, just to name a few. The protocol used depends on the operating systems in use and the individual requirements of the network in question.