Practice, drilling, memorization

Daniel Willingham:

What’s the difference between practice, drilling, and memorization?
In the psychological literature Practice has a formal definition, which I know through Anders Ericsson; I think it originates with him but am not certain. Practice includes feedback on performance, and it’s executed for the purpose of improvement. The distinction is important because it differentiates practice from performance (which is done for the pleasure of others) or play (which is done for one’s own pleasure) or the routine execution of a task (which is done to achieve a goal).
Thus, if I practice guitar I’m trying to improve, and I’m monitoring my performance for the sake of noting errors and thinking of new ways to do it. Performance and play of the guitar differ in obvious ways. Routine execution might apply to a task like handwriting. My handwriting is pretty bad, despite thousands of hours of execution, because during all of that time I wasn’t practicing. I was just writing to get something on paper.