I looked into the differences when buying my H2O 2 and I found a useful discussion at
https://www.e-reader-forum.de/ebook-...h2o-edition-2/ It's in German, but Google/Chrome translate will give you the gist of the discussion.
It's worth noting that the H2O 2 has a capacitive screen compared to the infrared on the original H2O. It is widely agreed that this makes the H2O 2 screen look a bit darker when the light is turned off. See the detailed photos here
http://aldus2006.typepad.fr/.a/6a00d...9021695970b-pi and here
http://www.bilder-upload.eu/show.php...1499848074.jpg But the H2O 2 looks to do a bit better on text blackness in those photos.