When I started with Documentum one among the first confusions that I had was this. Let me explain how are they different.
A Cabinet object is the highest level of Organization visible to the users in a Repository. Means Cabinets can exist only in the top level in the Repository. Cabinet object extends from Folder. But Any object that extends from dm_sysobject (ie means any object that can be saved in a repository) are stored in Cabinets. A Cabinet cannot be placed inside another cabinet or a folder and you need super user privileges to create or remove a Cabinet. But a user who has write access to cabinet can modify the attributes of a cabinet.
The Internal name of Cabinet is dm_cabinet and the r_object_id of cabinet always starts with “0c”
For Understanding Cabinets better, you can compare the Drive letters of your Home PC as a Cabinet. A Drive is always in the top level in the hierarchy. and you cannot save any data above the Drive level but you can create files in a Drive or in any folders located in the drive.
The Folders are means of organizing objects that can be saved (Any object that extends from dm_sysobject other than dm_cabinet) and it is used with combination of a Cabinet. In other words a Folder cannot exist without a Cabinet. All objects that are saved in a repository must be saved either in a folder, which is inside a cabinet, or it can be saved directly in a cabinet.
Folder extends from dm_sysobject and the internal name of folder is dm_folder and r_object_id of a dm_folder starts with “0b”
An object has to be linked with a folder and it can be linked with multiple folders