A collection is curated. A saved search is computed.
Use a collection when selection is editorial
“Revise these five chapters this week,” “candidate articles for Part II,” and “send these scenes to the beta reader” are deliberate sets. You may want your own order even when the items come from different places in the manuscript.
Use a saved search when the rule matters more than the members
“Every Draft scene,” “everything containing this phrase,” or “all sections of this type” should update as the project changes. Maintaining that list manually would create stale administration.
Why not use folders for everything?
A folder changes structural location. A chapter may simultaneously belong to the actual book, this week's revision set, and an editor's review set. Temporary attention should not force permanent movement.
assets/img/bmaker/bmaker-explained-collection-search-01.webpThe useful test
If you would say “I choose these items,” use a collection. If you would say “show me whatever matches this condition,” use a saved search.