These steels are made by Aichi Steel, a subsidiary of the Toyota group who manufacturers roughly 40% of Japanese steel.
AUS10 is close to the VG10 however it has slightly less Chromium (1% less) and has added Manganese (0.5), Nickel (0.49) and traces of Silicon and Phosphorus. Much like Chromium, Nickel helps reduce corrosiveness of the steel and the added Manganese hardens the steel and reduces the resistence to wear. This has seen it used to adjust steel used for train tracks, safes, prison bars etc however within the knife a smaller amount is used.
The AUS10 is commonly used in high end knives and is favorite for when making a Damascus finish (by adding acid at the end - Damascus finish is created by what is done with the steel not which steel are you using).
The steel cauldron is made up like this: