Services such as Dropbox, Google Drive and OneDrive are cloud synchronising tools that store data on your harddisk and save it on the cloud. You need to keep your data on your device to be able to access it. In short, they are file synchronising tools.

Imagine a large amount of confidential data being uploaded to the cloud and made accessible to many devices. If you had to eliminate some of said documents you would have to wait for all the devices to synchronise again with the cloud and would have no guarantee that they do. What a nightmare!

A document management system is much more than "just" a synchronisation tool. It is a business wide document management system (DMS) that keeps all your data centrally stored. All your coworkers access it through their devices. This way everyone is using the latest version of every document and not using discarded ones. A DMS additionally offers many management, audit, reporting and consulting applications. It allows you indexing, search, locking and versioning of documents. Automated lifecycles of data with automated elimination or archiving of files. Much more than just online storage.

Preset filing structures (such as project or customer dossiers) and document titles have to be input manually on the Fileshare tools and you can add no additional information to a file that links to a category such as Language, or project number, etc...

Tipically document management systems are built to manage the lifecycle of a certain file that needs indexing or to be shared.