This is kind of interesting...

Kindle readers read novels. Physical book readers read self-help.

Now, granted, this is based on the top 10 sellers of each type in March alone.  There is more diversity in terms of genre in paper format, but each of the top 10 which were non-fiction were what we might call light reading (such as self-help) or in the case of the children's books and Dungeons & Dragons reference manual, heavily illustrated rather than text-intensive (also a reason to read in physical format rather than Kindle--artwork doesn't translate to the traditional e-reader, anyway, not like it would on the Fire, and neither could capture the artwork as well as paper).  The two novels that were on the paper format list were, incidentally, A Wrinkle in Time and Ready Player One, both of which have recently been released as major motion pictures.  Each of the books on this list did have Kindle editions, too.

On the Kindle side, 90% were fiction mainly thrillers.  The one that wasn't was a biography of a murderess in a sensational historical case.

I'll let you draw your own conclusions, albeit from a very small sample.  But I did find it rather intriguing.  I'd like to see the statistics for a year, for example, or say, with the top 100 books in each category over that timeframe.