Keyed Alike- Locks with the same key
When keyed alike, all locks in a set can be opened with the same key. This option is beneficial when multiple locks are used by the same person so that only one key needs to be used. Examples- all the padlocks in a set can be opened using the same key. All the cabinet doors and drawers within an office could be opened with the same key.
Keyed Different- Locks with different keys. Each lock has its own unique key and can not be opened by the other keys from the same locks. Examples- Each padlock would require a different key to open. Each cabinet lock in a cabinet would require a different key to open.
See also What Does Keyed alike mean?
What is Difference between KD, KA and MK?