When should you use a file server, & when should you use a NAS device? Personally, I've always got spare parts laying around, so it doesn't cost me anything to throw together a file server, but NAS would likely be better in some circumstances. HDDSaver tells us exactly when that'd be...

"NAS products range from things as basic as external hard drive enclosures which are attached to a router to large, multi-drive devices which house a controllable operating system, a switch, and other useful accessories."