Q: “What are the differences between Channel, Key and Poly Aftertouch?”
A: With Channel Aftertouch, all notes respond the same. For example, if you play a C major triad (C, E, & G) and lean into the C only, all three notes will respond as though they were being leaned into. Key and Poly Aftertouch are the same thing and differ from Channel Aftertouch in that individual keys are affected by your performance. Using the example from before for instance, while leaning into the C only the E & G will not be affected.