How to distinguish old-fashioned textbook from online textbook?

I work for a publishing company, and we call our online books "e-books" and our printed books ... well ... "printed books." (So I concur with @Josh 's comments above.)

This Wikipedia article has a suprisingly complete explanation of e-books and their evolution:

An electronic book (or e-book) is a book publication made available in digital form, consisting of text, images, or both, readable on the flat-panel display of computers or other electronic devices. Although sometimes defined as "an electronic version of a printed book," some e-books exist without a printed equivalent.

So, I would write that one sentence in your paragraph like this:

But then I read that R uses an e-book and H uses a printed book.

(Note the article an, not a, before e-book.)

Various possibilities; among the more common are hard copy and print (or printed) textbook).