Which difference between commerce file & purchasable commerce file?

I am setting up a shop with Drupal Commerce for digital files selling.
I shifted from Ubercart, as I finally got the positive logic that is behind DC: dualize product definition and contents/product displays.
After long time afraid about it, now I am loving the possibilities it opens to manage contents in a Drupal site, and link purchasable products to them.

So I am using (and have to ...) Drupal Commerce file module.
After installing it, I have found these two types of field possible defining a product: commerce file & purchasable commerce file
Which functional difference between them? The GUIs for both of them seem to be the same, with License duration, numbers of downloads, ecc. parameters to be defined ...

Which I should better use for?

Thanks for any help.

PS: Would be nice to have more tutorials for Drupal Commerce File, to get how to correctly set up and manage the file buying process, explaining the granting of licenses on them and what ever ...
The module's logic seem nice, but there are issues regarding buying process finalization and licensed files granting, and even access to them (when granted)
Any somewhere around yet?

Posted: Sep 23, 2011