Contents of Collections vs Binder

Newish to Scrivener and trying to get the hang of “Collections”…I am compiling not a book, per se, but a knowledge base of sorts. I want to use Collections for things like “Supporting Material” “Needs Research”…etc. Do documents exist in both Binder and Collections, essentially mirrors of one another. If I create a document in Binder and then move it into a Collection, it remains in both. If I delete it from the Collection or from the Binder, does it stay in the other place?

The Binder is the canonical list of everything in the project. If it exists, it’s in the Binder somewhere. If you delete something from the Binder, it’s gone. (Actually it moves to the Project Trash until you empty the Trash.)

A Collection is a subset of the Binder, either defined manually by you or through a search. With manually created Collections, deleting an item simply removes it from the Collection. Its location in the Binder is unchanged. Search Collections won’t let you add or remove items, you can just change the search criteria.