🚀 go-pugleaf

Well, if you really want to go over the differences, you can check out Adobe's tech doc which explains it. PDF files are freely distributable and can be used in Acrobat Reader or Acrobat or any other PDF viewer. ebooks are proprietary to the Adobe ebook Reader and are normally served off a content server for security purposes. That way publishers can limit whether these ebooks are printed/transfered/etc. 

Although many people call regular PDF files "ebooks" (probably because they are electronic), there are some pretty big differences. Yes, I can create an entire book in PDF format. But I can also create a publisher-controlled ebook to try to enforce copyright issues. 

The point being, you really don't have much of a reason to be using the ebook reader over the regular Acrobat Reader unless you are opening ebooks and not plain ol' PDF files.