better is not very easy to say... they are different for sure. Here's a brief rundown on steels made by hitachi-
The most basic and cheap steels made by hitachi are the sk steels (sk3, sk4, sk5). These are pretty simple carbon steels that arent particularly pure (sulfur and phosphorus). When you increase the purity a bit, you get yellow steel (yellow 3, yellow 2). These are more pure than the sk steels, but still not super pure. The lower the number, the more carbon the steel has (i.e. sk3 has more carbon than sk4, and yellow 2 has more carbon than yellow 3). When you increase the purity of yellow steel, you get white steel. (white 3, white 2, and white 1). White steel is a simple, pure carbon steel that takes a great edge, sharpens easily, and has good toughness. From white steel, when you add a bit of chromium and tungsten, you get blue steel (i.e. white #2 plus a bit of chromium and tungsten yields blue #2... the carbon level is equal). Blue steel has better edge retention and corrosion resistance than white steel at the cost of not getting quite as sharp, being a bit more difficult to sharpen, and being a bit more brittle. Blue #1 would be white #1 with chromium and tungsten added. Blue super is created by taking blue #1 and adding even more carbon, chromium, and tungsten. It has the best edge retention and corrosion resistance at the cost of being more brittle and tougher to sharpen. So if you wanted to make a scale with the white and blue steels most often used in kitchen knives, with one side being the easiest to sharpen and having the best toughness and the other side having the best edge retention and corrosion resistance (but being a bit more brittle), on the first end you would have white #2 (or white #3, but #2 is more common) and on the other side, blue super.
Does that make sense?
