What is the difference between a domain and work group?

Basically, the main difference is that a domain has a dedicated server. That is, a computer especifically designes to be the "domain controller". The most notable difference is with security and permissions. With a domain, user accounts are set entirelly on the server, and any computer on the domain can use those, thus getting the permissions of that user. With a domain you can use your very same account with the same rights on any PC on the domain, just because the login is performed at the server. The work group is different in that all machines are "equal". There is no dedicated server, at least from a software perspective. Every PC has its own users and passwords, and thge local administrator is responsible for allowing other computers to use the local files on shared folders. Often, work groups are found in home networks and small offices, while domains are used for larger networks mainly on medium to large enterprises. You can be either a domain user or a work group user, not both at the same time. You specify if the computer is member of a domain or belongs to some workgroup. There can be however a domain and a workgroup on the same network, and you can access both, just need to know a domain user/password (from the domain server) or have enought rights on the work group machines.