Japanese and English versions are the same, B6 size.
Japanese version has transparent dust cover...
Both is printed on quality white paper and print quality is on par.
I'm glad Seven Seas licensed this series because the quality is astounding. It is damn heavy, the paper so thick that it can give a paper cut, translation is decent. If you want to buy Dai Dark, you can order without hesitation because Seven Seas respects the series. Just don't buy it from amazon, their shipping is garbage.