Since I have been using the Butterfly Petr Korbel blade (Japan version) for a very long time and I had the pleasure of trying the Europe version as well, I can give you a full-fledged comparison. Let's start with the visual inspection: The premium machining of the Japan version as opposed to the Europe version is immediately noticeable when both are in front of you, the Japan version has serial numbers.
Handle design: The grip of both is very handy - very comfortable (for small and medium hand players), the handle of the Japan version is a bit wider and flatter, but I have tried it before with a much wider handle - blade made with grip e.g. Gewo Aruna Carbon ALL+ compared to which the Petr Korbel Japanese version is noticeably thinner, the handle of the Europe version is thinner than the Japan version and more convex, when playing, both were very comfortable for me.
Game features: For the sake of the comparison test, I borrowed the Europe version from one of my fellow players, and since I am an attacking player FH Yasaka Rakza X (max version), BH Yasaka Rakza Z (max version) I use 5 layers of Revolution Nr.3 glue, I put the same rubbers on the Europe version, my experience is that the Japan version is noticeably faster, however, the ball detection is very similar, spinning the ball from under the table with both blades is very easy, the extra speed of the Japan blade is provided by modifying the stacking of the changed wooden layers, and the Japan version is a little thicker and heavier, mine is 95 grams, (the Europe version is 88 grams), it is true for both versions that the head size of the blade is larger, which also means a larger hit area, in case of max rubbers or 2.1 spongy rubbers you get a head-heavy racket, the Japan version is a better balanced blade and the handle did not feel hollow during playing, I felt this with the Europe version. I don't like this feeling, but there are players who do, so I won't bring this up as a negative for the Europe version. Both blades use rubbers with a medium-hardness sponge for the best pairing.
Final word: Both blades are great blades in their price range, the Japan version is a premium quality blade that doesn't lack strength and ball sensing. For those who are small and medium-handed players and want a great, premium-crafted blade with great ball detection that doesn't lack speed, I can recommend the Butterfly Petr Korbel Japan version. The Europe version is slower, but with more power and fast rubbers, it will be fast enough for offensive play.