The iPad with ios employes a different file architecture/paredyme.
The iPad supports applications. You run applications. Applications may create and access only their own files. Applications may organize their files anyway they feel like. Some have folders some do not.
ios focus is on security. By assigning a file to one application it makes for a more secure environment. A "bad" application can only mess with it own files. ios prevents it from messing with other files on the system. You will observe that there are no known viruses on ios. Man, drive letters are so '70s.
There is no system wide files system.
Robert