What are the options for letting users organize their data in a complex SaaS product? Is there a name these patterns go by? And what patterns make sense when?

For example, here are a couple options I see in use:

1. Hierarchies/Folders: creating a tree, where data can be stored at each level. Think classic email interfaces.

2. Tags: A list of "tags" (ie strings) can be attached to each piece of data. Each tag acts as a category, allowing the user to search/filter. For example, gmail, stackoverflow, etc.

3. Labels: A list of key/value pairs (ie string -> string) that allow users to create their own metadata fields for data, and values for those fields. More flexible and more complex than tags. For example, kubernetes labels and annotations.

Anything else?