When you open Kontakt 4 and select a sound, you will see the on-screen keyboard has coloured keys towards the bottom of the keyboard, (Assuming the sound selected has multiple articulations) these are your articulation controls, (A standard used by software instruments (VST etc.) however because an arranger keyboard uses the lower part of the manual for accompaniment, you cannot normally access them, without first moving them further up the range and re-saving the sound, (One of the limitations of easy play arrangers) therefore arranger manufactures added physical buttons to do the same job, with the only downside being the number of buttons that arranger manufactures provide, is normally well short of the number of keys used in software instruments. (This is done as arrangers are designed for home players, and so easy play is of more importance then having a professional player’s arsenal at their disposal)

Hope this helps

Bill