User VFS, the COW and the S folders.....
Standard users will read and write from the regular directory (with
relaxed ACL’s) while elevated processes will read and write to the “S”
version.
This is further explained here
http://blogs.technet.com/b/gladiatormsft/archive/2014/08/29/app-v-5-on-the-now-sometimes-immutable-package-cache-location.aspx
