Question: What's the difference between pools of pools and Ada 2012's new subpools?

[Shark8 <onewingedshark@gmail.com>]

I recently asked this question on Stackoverflow ( http://stackoverflow.com/questions/14840702/what-are-the-differerences-between-the-new-ada-sub-pool-features-and-pools-of-po ).

I haven't used pools at all, yet; so it's quite likely I'm missing something.

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-- Pool of Pools
----------------------------------
-- Minnesota: Land of 10,000 Lakes
type Minnesota(Size: Storage_Count) is new Root_Storage_Pool with private;
type Lake(Size: Storage_Count) is new Root_Storage_Pool with private
     with Storage_Pool => Minnasota;
-- ...
type Pooled is [...] with Storage_Pool => Lake;

-------
-- Sub-Pools
----------------------------------
  type Pond(Size: Storage_Count) is new Root_Storage_Pool_With_Subpools with private;
  subtype My_Handle is Subpool_Handle;

[Note: examples uncompiled, just for illustrative purpose]