Let me tell it like it is...
B&N decided to use a different flavor of DRM that uses the users name and credit card number to unlock the eBook. B&N did manage to get Adobe on board and Adobe added B&N's flavor of DRM to ADE. Sony being in competition for B&N decided not to allow B&N's flavor of DRM on Sony Readers because that would mean that those who do not remove DRM would not be able to buy any eBooks from B&N that contain DRM.
Sony does use ADE. Sony does not allowed B&N's DRM. You can buy ePub from any other online shop except B&N and Apple. Apple has their own oddities with iBooks so even if there was no DRM, they may not work. B&N's eBooks are standard ePub (when the DRM is removed or if there never was DRM).
Go look for Apprentice ALF using Google. You will be able to learn how to remove the DRM from your eBooks. Sorry I cannot give any more information on removing DRM, but is it a policy here not to.