Set Track Volume / Set Channel Volume

It’s probably trivial but what is the exact difference between these two pattern effect switches (03 and 0C)? So far, I’ve seen that 0C, the “Track” Volume, changes the tracks pre volume. What does the channel volume do?

I could be wrong, but I think the channel volume changes the velocity of a note. It has higher resolution than the velocity column since it goes from 0 to FF.