More than a hidden album
Hiding an album changes where it appears in an interface. Encryption changes how stored information is represented, so the readable photo is not simply left as an ordinary file in that storage.
Work together with your unlock method
Your pattern, PIN, or Face ID experience controls access to your collection. Storage protection is another part of that experience, working alongside the way you enter your vault.
Remember other copies
Importing a photo into a vault does not make every other copy disappear. Review copies in your camera roll, recently deleted items, other backups, and messages according to the privacy you want.