The postcards include the other three members not included in the Korean version. They include two beautiful photos of Myungsoo (I prefer these a lot more than the Korean ones), one of Dongwoo, Woohyun and Sunggyu, and two artistic ones. I really like the lighted up one! The order is from left to right, top to bottom.
I'm so glad I was able to buy the Japanese version! While the book itself is the same (at least for non-Koreans or non-Japanese, that's how it feels), the first press extras are such a nice bonus.