Document Management System allows you to keep your files in a orderly manner.
And it is customized for business purpose.
There will be multiple user group under the admin account.
The admin will be able to create different user and group.
For example you will be able to create a Finance, Marketing, Admin group. And whereby users under Finance can only see the files shared with Finance group and Marketing users can only see the files shared with Marketing group.
But the admin will be able to see all the files and have all access over them. So this allow you to have a systematic file sharing system in your company. And also increases security level.