What difference does the $LANG variable make?

Everyone knows that changing the language setting $LANG can change the way in which symbols such as € are displayed, however they may not be aware of how it can subtlety change the way in which items such as the datestamp on files e.g.

With the $LANG set to "C":
crw-rw-rw-    1 root     system        2,  3 Oct 6 2011  /dev/zero

  Snapshots for /test
  Current  Name         Time
!          snapshot1    Tue Aug 14 14:40:52 2012
! *        snapshot2    Tue Aug 14 14:45:09 2012

With the $LANG set to "EN_US":
crw-rw-rw-    1 root     system        2,  3 Oct 06 2011  /dev/zero

   Snapshots for /test
  Current  Name         Time
!          snapshot1    Tue Aug 14 14:40:52 CEST 2012
! *        snapshot2    Tue Aug 14 14:45:09 CEST 2012

Whilst these changes can seem purely cosmetic, and appear to make no difference, if you are running automated tasks such as backup scripts this can make them fail or behave oddly.