What is the thing professionals can do that amateurs can’t?
Okay, there are a lot of things – not least, the facility on their instrument, their reliability, their reading chops, etc.
Maybe the most significant skill pros have is the ability to adjust in the moment, while keeping the big picture in mind.
If I say, “Add an intro in the same key, and we’re going to do a three-time tag on the end,” a professional understands the framework of the piece well enough to implement that seamlessly. Young musicians and amateurs often struggle to shift from the specific musical framework they learned, because for them, each moment is distinct and significant.
As we come in contact with more and more music, we begin to pay less attention to individual moments and more attention to the overall framework. When that happens, it becomes trivial to make minor or even significant changes to a performance because the framework stays intact.