1.BT is the Japanese standard, and SK is the German standard.
2. The flanges are different. The thickness of the flange of the BT tool holder is larger, while the thickness of the flange of the SK tool holder is smaller.
3. The key grooves at both ends of the BT tool holder have the same depth and are not milled through. The key grooves at the two ends of the SK tool holder have different depths and are milled through.
4. The positioning gaps for installing the knife are different.
Similar points: the taper of the tool holder is 7:24, so if you do not use a manipulator but change the tool manually, the BT tool holder and the SK tool holder can generally be used interchangeably, you just need to change the corresponding Latin one.